UNITED STATES 
                       SECURITIES AND EXCHANGE COMMISSION 
                             WASHINGTON, D.C. 20549 
 
                                  SCHEDULE 13D 
 
                    UNDER THE SECURITIES EXCHANGE ACT OF 1934 
 
                               (AMENDMENT NO. 4)* 
 
                         REGENERON PHARMACEUTICALS, INC. 
                                 (Name of Issuer)  
 
                          COMMON STOCK, $.001 PAR VALUE 
                         (Title of Class of Securities) 
 
                                   00075886F1 
                                  (CUSIP Number) 
 
                                             with a copy to: 
     George A. Vandeman, Esq.                Michael W. Sturrock, Esq. 
     Senior Vice President,                  Latham & Watkins 
     General Counsel and Secretary           633 West Fifth Street 
     Amgen Inc.                              Suite 4000 
     Amgen Center                            Los Angeles, California  90071 
     1840 DeHavilland Drive                  (213) 485-1234 
     Thousand Oaks, CA  91320-1789 
     (805) 447-1000               
 
                 (Name, Address and Telephone Number of Person 
                Authorized to Receive Notices and Communications)
                                                              
 
                                 April 15, 1996
                      (Date of Event which Requires Filing 
                               of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d- 1(b)(3) or (4), check the following box / /. 

Check the following box if a fee is being paid with the statement. / / (A fee is
not required only if the reporting person: (1) has a previous statement on file
reporting beneficial ownership of more than five percent of the class of
securities described in Item 1; and (2) has filed no amendment subsequent
thereto reporting beneficial ownership of five percent or less of such class.)
(See Rule 13d-7.) 

NOTE:  Six copies of this statement, including all exhibits, should be filed
with the Commission.  SEE Rule 13d-1(a) for other parties to whom copies are to
be sent. 
 
*The remainder of this cover page shall be filled out for a reporting person's
initial filing on  this form with respect to the subject class of securities,
and for any subsequent amendment  containing information which would alter
disclosures provided in a prior cover page.    

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes). 
 




 
 
 
                                  SCHEDULE 13D 
 
 
  CUSIP No. 00075886F1                        Page 2 of 5 Pages 
 
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     1   NAME OF PERSON 
           AMGEN INC. 
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     2   CHECK THE APPROPRIATE BOX IF MEMBER OF A GROUP*   (a)     / /
                                                           (b)     / /         
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     3   SEC USE ONLY 
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     4   SOURCE OF FUNDS* 
           WC 
- --------------------------------------------------------------------------------
     5   CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS           / /
         REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) 
- --------------------------------------------------------------------------------
     6   CITIZENSHIP OR PLACE OF ORGANIZATION 
           DELAWARE 
- --------------------------------------------------------------------------------
                     7    SOLE VOTING POWER 
                            5,138,766
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 NUMBER OF SHARES    8    SHARED VOTING POWER 
 BENEFICIALLY               N/A 
 OWNED BY EACH     -------------------------------------------------------------
 REPORTING PERSON    9    SOLE DISPOSITIVE POWER 
 WITH                       5,138,766
                   -------------------------------------------------------------
                    10    SHARED DISPOSITIVE POWER 
                            N/A 
- --------------------------------------------------------------------------------
    11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH 
         REPORTING PERSON 
           5,138,766
- --------------------------------------------------------------------------------
    12   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11)             / /
         EXCLUDES CERTAIN SHARES* 
           N/A 
- --------------------------------------------------------------------------------
    13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 
           24.1%
- --------------------------------------------------------------------------------
    14   TYPE OF PERSON REPORTING* 
           CO 
- --------------------------------------------------------------------------------
                * SEE INSTRUCTIONS BEFORE FILLING OUT 
 

          This Amendment No. 4 to Schedule 13D is being filed by Amgen Inc., a 
Delaware corporation (the "Reporting Person"), to amend the Schedule 13D filed 
on July 26, 1995, as amended by Amendment No. 1 filed on September 25, 1995,
Amendment No. 2 filed on December 6, 1995 and Amendment No. 3 filed on 
March 5, 1996 (the "Schedule 13D"), relating to the common stock, $.001 par 
value per share (the "Common Stock") of Regeneron Pharmaceuticals, Inc. (the 
"Issuer").  Unless otherwise indicated, all capitalized terms used herein but 
not defined herein shall have the meaning assigned to them in the Schedule 13D.

ITEM 3.   SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION.

          Item 3 to Schedule 13D is hereby amended and supplemented to add 
the following information:

          The source of the $48,000,000 used for the Reporting Person's 
purchase (as describeed in Item 5(c) below) of 3,000,000 shares of Common 
Stock and warrants to purchase 700,000 shares of Common Stock at an exercise 
price of $16 per share (the "Warrants") was the working capital of the 
Reporting Person.

ITEM 4.   PURPOSE OF TRANSACTION. 
  
          Item 4 to Schedule 13D is hereby amended and restated in its 
entirety as follows:

           The Reporting Person acquired the 3,000,000 shares of Common Stock 
and the Warrants for investment purposes.  

          As a result of an August 1990 agreement between the Reporting 
Person and the Issuer, further described in Item 6 below, the Reporting 
Person is subject to a number of so-called "standstill" restrictions (the 
"Standstill Restrictions").  One Standstill Restriction generally prohibits 
the Reporting Person from acquiring more than 20% of the outstanding shares 
of capital stock of the Issuer on a fully diluted basis.  Other Standstill 
Restrictions generally prohibit the Reporting Person from making acquisition 
proposals to the Issuer and engaging in the solicitation of proxies.  SEE 
Item 6 below, for additional information with respect to the Standstill 
Restrictions.  ALSO SEE Item 6, below, for a discussion of certain (i) 
registration rights with respect to certain of the Shares beneficially owned 
by the Reporting Person and (ii) transfer restrictions relating to certain of 
the Shares beneficially owned by the Reporting Person.

          Subject to the Standstill Restrictions and depending on general 
market and economic conditions affecting the Issuer and other relevant 
factors, the Reporting Person may purchase additional shares of Common Stock 
or dispose of some or all of its shares of Common Stock or the Warrants from 
time to time in open market transactions, private transactions or otherwise.

          Except as set forth in the Schedule 13D, the Reporting Person has no
present plans or proposals with respect to any material change in the Issuer's
business or corporate structure or which relate to or would result in:

               (1)  the acquisition by any person of additional securities of
     the Issuer, or the disposition of securities of the Issuer;

               (2)  an extraordinary corporate transaction, such as a merger,
     reorganization or liquidation, involving the Issuer or any of its
     subsidiaries;

               (3)  a sale or transfer of a material amount of assets of the
     Issuer or any of its subsidiaries;

               (4)  any change in the present board of directors or management
     of the Issuer, including any plans or proposals to change the number or
     term of directors or to fill any existing vacancies on the board;

               (5)  any material change in the present capitalization or
     dividend policy of the Issuer;

               (6)  changes in the Issuer's charter, bylaws or instruments
     corresponding thereto or other actions which may impede the acquisition of
     control of the Issuer by any person;

               (7)  causing a class of securities of the Issuer to be delisted
     from a national securities exchange or cease to be authorized to be quoted
     in an inter-dealer quotation system of a registered national securities
     association;

               (8)  a class of equity securities of the Issuer becoming eligible
     for termination of registration pursuant to Section 12(g)(4) of the
     Securities Exchange Act of 1934; or

               (9)  any action similar to any of those enumerated above.
 
ITEM 5.   INTEREST IN SECURITIES OF THE ISSUER. 
 
          Paragraphs (a) through (e) of Item 5 to Schedule 13D are hereby 
amended and restated in their entirety as follows: 
 
          (a) As of the close of business on April 15, 1996, the Reporting 
Person beneficially owned 5,138,766 shares of Common Stock (which includes 
788,766 shares of Common Stock issuable if and when the shares of Class A 
Stock are converted into shares of Common Stock and 700,000 shares of Common 
Stock issuable if and when the Warrants are exercised). Such shares of Common 
Stock constitute approximately 24.1% of the total number of shares of Common 
Stock outstanding as of April 15, 1996, assuming the conversion of the shares 
of Class A Stock beneficially owned by the Reporting Person into shares of 
Common Stock and the issuance of 700,000 shares of Common Stock upon exercise 
of the Warrants, and based upon 16,826,838 shares of Common Stock outstanding 
as of April 12, 1996. The outstanding shares of Class A Stock not 
beneficially owned by the Reporting Person are excluded in calculating the 
percentage ownership of the outstanding shares of Common Stock by the 
Reporting Person for purposes of the Schedule 13D, but are included in 
calculating the percentage ownership of the outstanding shares of capital 
stock by the Reporting Person for purposes of the Standstill Restrictions.

          (b)  The Reporting Person has the sole power to vote or to direct the 
vote, and the sole power to dispose or to direct the disposition of, the Shares 
beneficially owned by the Reporting Person. 
 
          (c)  On April 15, 1996, the Reporting Person acquired from the 
Issuer in a private transaction 3,000,000 shares of Common Stock and the 
Warrants, for a total purchase price of $48,000,000.

                               PAGE 3 OF 5 PAGES 
 
 
          (d)  Not applicable. 
 
          (e)  Not applicable. 
 
ITEM 6.   CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT
          TO SECURITIES OF THE ISSUER.

          Item 6 to Schedule 13D is hereby amended and restated in its 
entirety as follows:

          Pursuant to the Class D Convertible Preferred Stock Purchase 
Agreement dated as of August 31, 1990 by and between the Issuer and the 
Reporting Person (the "Purchase Agreement"), the Reporting Person acquired, 
for an aggregate purchase price of $15,000,000, beneficial ownership of 
767,656 shares of Class D Preferred Stock in 1990.  In 1991, the Issuer 
effected a recapitalization and an initial public offering of shares of its 
Common Stock and following such recapitalization and offering the Reporting 
Person's 767,656 shares of Class D Preferred Stock were automatically 
converted into 788,766 shares of Class A Stock.  As described in the Issuer's 
Restated Certificate of Incorporation, the shares of Class A Stock are 
super-voting (each share having 10 votes instead of one), are subject to 
certain transfer restrictions and are optionally convertible, at any time and 
at the option of the holder thereof, and mandatorily convertible, upon the 
transfer of such shares to someone other than a permitted transferee, into an 
equal number of shares of Common Stock.

          Section 9 of the Purchase Agreement also contains the Standstill
Restrictions referred to in Item 4.  The Reporting Person has agreed, among
other things, for a period of 20 years or the term of a collaboration agreement
between the Issuer and the Reporting Person, whichever is earlier, (i) not to
purchase any shares of the capital stock of the Issuer if its ownership position
in the Issuer on a fully diluted basis would be greater than 20% of the then
outstanding capital stock of the Issuer, (ii) not to engage in the solicitation
of proxies and (iii) not to make any acquisition proposal.  There are certain
very limited circumstances in which the Standstill Restrictions would not apply.

          The Issuer has also granted the Reporting Person customary demand 
and piggyback registration rights under Section 8 of the Purchase Agreement 
with respect to certain of the Shares beneficially owned by 
the Reporting Person.
          
          Section 11(d) of the Purchase Agreement also provides the Issuer with
certain rights of first refusal with respect to transfers by the Reporting
Person of certain Shares to competitors of the Issuer.

          Pursuant to a Stock and Warrant Purchase Agreement and Warrant 
Agreement both dated as of April 15, 1996, by and between the Issuer and the 
Reporting Person, the Reporting Person acquired from the Issuer in a private 
transaction 3,000,000 shares of Common Stock and the Warrants, for a total 
purchase price of $48,000,000.  The Warrants may be exercised any time on or 
before April 15, 2001.  As part of the same transaction the Issuer and the 
Reporting Person entered into a Registration Rights Agreement, dated as of 
April 15, 1996, pursuant to which the Issuer granted to the Reporting Person 
customary demand and piggyback registration rights with respect to the 
3,000,000 shares of Common Stock and the shares of Common Stock issuable upon 
exercise of the Warrants.

          The above descriptions of all of the above-mentioned agreements (the 
Agreements"), as well as the descriptions set forth in Item 4, are summaries 
only and do not purport to be complete descriptions of the terms of such 
Agreements.  These summaries are subject to, and are qualified in their entirety
by reference to, the detailed provisions of the Agreements, which are
filed as exhibits to this Schedule 13D.

ITEM 7.   MATERIAL TO BE FILED AS EXHIBITS.

          Item 7 to Schedule 13D is hereby amended and supplemented as 
follows:

7.3       Stock and Warrant Purchase Agreement, dated as of April 15, 1996, 
          by and between the Issuer and the Reporting Person.

7.4       Warrant Agreement, dated as of April 15, 1996, by and between the 
          Issuer and the Reporting Person.

7.5       Registration Rights Agreement, dated as of April 15, 1996, by and 
          between the Issuer and the Reporting Person.

 
                                PAGE 4 OF 5 PAGES 



                                    SIGNATURE

          After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.


                              AMGEN INC.



                              By: \s\ George A. Vandeman                        
                                  ---------------------------------------------
                                  Name:    George A. Vandeman
                                  Title:   Senior Vice President, General
                                           Counsel and Secretary





Dated:  April 18, 1996


                               Page 5 of 5 Pages



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                         STOCK AND WARRANT PURCHASE AGREEMENT

                                    by and between

                           REGENERON PHARMACEUTICALS, INC.

                                         AND

                                      AMGEN INC.




                             DATED AS OF:  APRIL 15, 1996






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- --------------------------------------------------------------------------------



                                  TABLE OF CONTENTS


                                                                            PAGE


ARTICLE I      DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . .  1

    1.1  Defined Terms . . . . . . . . . . . . . . . . . . . . . . . . . .  1
    1.2  Other Defined Terms . . . . . . . . . . . . . . . . . . . . . . .  2

ARTICLE II    ISSUANCE AND SALE OF SECURITIES. . . . . . . . . . . . . . .  3

    2.1  Issuance and Sale of Securities . . . . . . . . . . . . . . . . .  3

ARTICLE III   CLOSING. . . . . . . . . . . . . . . . . . . . . . . . . . .  3

    3.1  Closing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
    3.2  Documents to be Delivered . . . . . . . . . . . . . . . . . . . .  3

ARTICLE IV    REPRESENTATIONS AND WARRANTIES OF THE COMPANY. . . . . . . .  4

    4.1  Organization and Standing . . . . . . . . . . . . . . . . . . . .  4
    4.2  Capitalization. . . . . . . . . . . . . . . . . . . . . . . . . .  4
    4.3  Issuance of Shares. . . . . . . . . . . . . . . . . . . . . . . .  5
    4.4  Authority for Agreement . . . . . . . . . . . . . . . . . . . . .  5
    4.5  Governmental Consents . . . . . . . . . . . . . . . . . . . . . .  6
    4.6  Litigation. . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
    4.7  SEC Filings; Financial Statements . . . . . . . . . . . . . . . .  6
    4.8  No Undisclosed Liabilities. . . . . . . . . . . . . . . . . . . .  7
    4.9  Absence of Changes. . . . . . . . . . . . . . . . . . . . . . . .  7
    4.10 Intellectual Property . . . . . . . . . . . . . . . . . . . . . .  7
    4.11 No Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
    4.12 Offerings . . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
    4.13 Brokers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
    4.14 Clinical Trials . . . . . . . . . . . . . . . . . . . . . . . . .  8

ARTICLE V      REPRESENTATIONS AND WARRANTIES OF BUYER . . . . . . . . . .  8

    5.1  Investment. . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
    5.2  Authority . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
    5.3  Accredited Investor . . . . . . . . . . . . . . . . . . . . . . .  9
    5.4  Brokers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
    5.5  Clinical Trials . . . . . . . . . . . . . . . . . . . . . . . . .  9



                                          i



ARTICLE VI    INDEMNIFICATION. . . . . . . . . . . . . . . . . . . . . . .  9

    6.1  Survival of Representations, Etc. . . . . . . . . . . . . . . . .  9
    6.2  Indemnification . . . . . . . . . . . . . . . . . . . . . . . . . 10

ARTICLE VII   MISCELLANEOUS. . . . . . . . . . . . . . . . . . . . . . . . 10

    7.1  Legend. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
    7.2  Assignment. . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
    7.3  Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
    7.4  Choice of Law . . . . . . . . . . . . . . . . . . . . . . . . . . 12
    7.5  Entire Agreement; Amendments and Waivers. . . . . . . . . . . . . 12
    7.6  Counterparts. . . . . . . . . . . . . . . . . . . . . . . . . . . 12
    7.7  Invalidity. . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
    7.8  Headings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
    7.9  Expenses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
    7.10 Publicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
    7.11 Specific Enforcement. . . . . . . . . . . . . . . . . . . . . . . 13
    7.12 Further Assurances. . . . . . . . . . . . . . . . . . . . . . . . 13
    7.13 Section 912 of the New York Business Corporate Law. . . . . . . . 13


                                          ii



                         STOCK AND WARRANT PURCHASE AGREEMENT


              This Stock and Warrant Purchase Agreement, dated as of April 15,
1996 is by and between AMGEN INC., a Delaware corporation ("BUYER"), and
REGENERON PHARMACEUTICALS, INC., a New York corporation (the "COMPANY").

                                       RECITALS

              WHEREAS, Buyer wishes to purchase from the Company, and the
Company wishes to sell to Buyer, 3,000,000 shares of the Company's Common Stock
(the "SHARES");

              WHEREAS, Buyer wishes to purchase from the Company, and the
Company wishes to sell to Buyer, pursuant to the terms and conditions of the
Warrant Agreement (the "WARRANT AGREEMENT"), 700,000 Warrants (the "WARRANTS,"
and together with the Shares, the "SECURITIES").  Each of the Warrants shall be
exercisable for one share of Common Stock (individually, a "WARRANT SHARE" and
collectively, the "WARRANT SHARES"); and

              WHEREAS, Buyer and the Company desire to provide for the
foregoing purchases and sales and to establish various rights and obligations in
connection therewith.

                                      AGREEMENT

              NOW, THEREFORE, in consideration of the mutual covenants and
promises contained herein and for other good and valuable consideration the
receipt and adequacy of which are hereby acknowledged, the parties hereto agree
as follows:


                                      ARTICLE I

                                     DEFINITIONS

              1.1  DEFINED TERMS.  As used herein, the terms below shall have
the following meanings:

              "BDNF" shall mean brain-derived neurotrophic factor.

              "CLASS A COMMON STOCK" shall mean the shares of the Class A
Common Stock, par value $.001 per share, of the Company.

              "COLLATERAL AGREEMENTS" shall mean the Warrant Agreement and the
Registration Rights Agreement.



              "COMMON STOCK" shall mean the shares of the Common Stock, par
value $.001 per share, of the Company.

              "COMMISSION" shall mean the Securities and Exchange Commission.

              "EXCHANGE ACT" shall mean the Securities Exchange Act of 1934, as
amended, and the rules and regulations of the Commission thereunder.

              "NT3" shall mean Neurotrophin - 3.

              "PERSON" shall mean any individual, firm, corporation,
partnership, limited liability company, trust, unincorporated organization or
other entity or a government or agency or political subdivision thereof, and
shall include any successor (by merger or otherwise) of such Person.

              "PREFERRED STOCK" shall mean the shares of the Preferred Stock,
par value $.001 per share, of the Company.

              "REGISTRATION RIGHTS AGREEMENT" shall mean the Registration
Rights Agreement to be entered into as of the date hereof by and between the
Company and Buyer.

              "SECURITIES ACT" shall mean the Securities Act of 1933, as
amended, and the rules and regulations of the Commission thereunder.

              "WARRANT AGREEMENT" shall mean the Warrant Agreement to be
entered into as of the date hereof by and between the Company and Buyer.

              1.2  OTHER DEFINED TERMS.  The following terms shall have the
meanings defined for such terms in the Sections set forth below:


                                          2



         TERM                                    SECTION
         ----                                    -------

         Buyer                                   Preamble
         Closing                                   3.1
         Company SEC Reports                       4.7
         Reserved Plan Shares                      4.2
         Securities                              Recitals
         Securities Purchase Price                 2.1
         Shares                                  Recitals
         Warrant Agreement                       Recitals
         Warrants                                Recitals
         Warrant Share                           Recitals
         Warrant Shares                          Recitals
         1995 Balance Sheet                        4.8


                                      ARTICLE II

                           ISSUANCE AND SALE OF SECURITIES

               2.1  ISSUANCE AND SALE OF SECURITIES.  Upon the terms set forth
herein, the Company will issue and sell to Buyer, and Buyer will purchase from
the Company, the Shares and the Warrants for an aggregate price of $48 Million
in immediately available funds (the "SECURITIES PURCHASE PRICE").


                                     ARTICLE III

                                       CLOSING

               3.1  CLOSING.  The closing of the transactions contemplated
hereby (the "CLOSING") will take place at the offices of Skadden, Arps, Slate,
Meagher & Flom, 919 Third Avenue, New York, New York 10022 at 5:00 p.m. New York
time on the date hereof.

               3.2  DOCUMENTS TO BE DELIVERED.  At the Closing, the Company
shall deliver to Buyer, against payment in full of the Securities Purchase
Price, (i) certificates for the Shares in such denominations as Buyer has
requested, dated the date hereof and registered in the names requested by Buyer,
(ii) certificates for the Warrants in such denominations as Buyer has requested,
dated the date hereof and registered in the names requested by Buyer, (iii) each
of the Collateral Agreements, which shall have been duly authorized, executed
and delivered by the Company and shall be in full


                                          3



force and effect and (iv) an opinion of Paul Lubetkin, General Counsel to the
Company, in form and substance reasonably satisfactory to Buyer, substantially
to the effect specified in SECTIONS 4.1 THROUGH 4.5, with such exceptions and
qualifications as are customary and reasonable under the law of the applicable
jurisdiction.  In rendering such opinion, such counsel may rely upon
certificates of public officers and, as matters of fact, upon certificates of
duly authorized representatives of the Company, PROVIDED, that copies of such
certificates shall be contemporaneously delivered to Buyer.


                                      ARTICLE IV

                          REPRESENTATIONS AND WARRANTIES OF
                                     THE COMPANY

               The Company hereby represents and warrants to Buyer as of the
date hereof as follows:

               4.1  ORGANIZATION AND STANDING.  The Company is a corporation
duly organized and validly existing under the laws of the State of New York and
has full corporate power and authority to own and lease its property, to conduct
its business as presently conducted and as proposed to be conducted by it and to
execute and deliver this Agreement and each of the Collateral Agreements.  The
Company has full corporate power and authority to perform and to carry out the
transactions contemplated by this Agreement and each of the Collateral
Agreements.  The Company is qualified to do business and in good standing in New
York and in each jurisdiction where it does business or owns property except
those jurisdictions where the failure to be so qualified and in good standing
would not have a material adverse effect on its business or property.  The
Company has furnished to Buyer true and complete copies of its Restated
Certificate of Incorporation and Bylaws, each as amended to date and presently
in effect.

               4.2  CAPITALIZATION.  As of April 12, 1996, the authorized
capital stock of the Company consisted of the following: (a) 60,000,000 shares
of Common Stock, of which (i) 16,826,838 shares were issued and outstanding,
(ii) 5,203,942 shares were reserved for future issuance upon conversion of the
Class A Common Stock, each share of the Class A Stock being convertible into one
share of Company Common Stock, and (iii) 3,789,626 shares were reserved for
future issuance under the Company's 1990 Amended and Restated Long-Term
Incentive Plan (the "RESERVED PLAN SHARES"); and (b) 40,000,000 shares of Class
A Common Stock, of which 5,203,942 were issued and outstanding, and (c)
30,000,000 shares of Preferred Stock, none of which were issued and outstanding.
No material change in such capitalization has occurred between April 12, 1996
and the date hereof, and there has been no reduction whatsoever in the


                                          4



number of shares of any class of the Company's outstanding capital stock.  All
of the issued and outstanding shares of Common Stock, Class A Stock, and
Preferred Stock have been duly authorized, and all of the issued and outstanding
shares of the Common Stock and the Class A Common Stock are validly issued and
are fully paid and non-assessable.  Except as set forth in the Company SEC
Reports hereto or as provided in this Agreement, there is not, nor upon the
consummation of the transactions contemplated herein, will there be, (i) any
subscription, warrant, option, convertible security or other right (contingent
or otherwise) to purchase or acquire any shares of capital stock of the Company,
(ii) any commitment of the Company to issue any subscription, warrant, option,
convertible security or other such right or to issue or distribute to holders of
any shares of its capital stock any evidences of indebtedness or assets of the
Company, or (iii) any obligation of the Company (contingent or otherwise) to
purchase, redeem or otherwise acquire any shares of its capital stock or any
interest therein or to pay any dividend or make any other distribution in
respect thereof.  Except as set forth in the Company SEC Reports or as provided
in this Agreement, no Person is entitled to, nor upon the consummation of the
transactions contemplated herein will any Person be entitled to, (i) any
preemptive or similar right with respect to the issuance of any capital stock of
the Company, or (ii) any rights with respect to the registration of any capital
stock of the Company under the Securities Act.

               4.3  ISSUANCE OF SHARES.  The issuance, sale and delivery of the
Securities in accordance with this Agreement, and the issuance and delivery of
the Warrant Shares issuable upon exercise of the Warrants, have been duly
authorized and reserved for issuance, as the case may be, by all necessary
corporate action on the part of the Company (no consent or approval of the
stockholders of the Company being required by law, by the Restated Certificate
of Incorporation or Bylaws of the Company, or the qualification criteria of the
Nasdaq National Market), and the Securities when so issued, sold and delivered
against payment therefor in accordance with the provisions of this Agreement,
and the Warrant Shares issuable upon exercise of the Warrants, when issued upon
such exercise, will be duly and validly issued, fully paid and non-assessable
and not subject to preemptive or any other similar rights of the shareholders of
the Company or others and free, at time of issuance, of all restrictions on
transfer subject to restrictions on transfer imposed by applicable federal and
state securities laws.

               4.4  AUTHORITY FOR AGREEMENT.  The execution, delivery and
performance by the Company of this Agreement and each of the Collateral
Agreements have been duly authorized by all necessary corporate action, and this
Agreement and each of the Collateral Agreements have been duly executed and
delivered and constitute valid and binding obligations of the Company
enforceable in accordance with their respective terms, subject to bankruptcy or
equitable laws that might affect the enforceability of this Agreement and each
of the Collateral Agreements.  The execution


                                          5



and delivery by the Company of this Agreement and each of the Collateral
Agreements, and the consummation by the Company of the transactions contemplated
hereby and thereby (including, without limitation, the issuance and sale of the
Securities and the Warrant Shares), will not violate any provision of law and
will not conflict with or result in any breach of any of the terms, conditions
or provisions of, or constitute a default under, or result in the creation of
any lien, security interest, charge or encumbrance upon any of the properties,
assets or outstanding capital stock of the Company, under the Company's Restated
Certificate of Incorporation, or Bylaws, or any indenture, lease, agreement or
other instrument to which the Company is a party or by which it or any of its
properties is bound, or any decree, judgement, order, statute, rule or
regulation applicable to the Company.

               4.5  GOVERNMENTAL CONSENTS.  No consent, approval, order or
authorization of, or registration, qualification, designation, declaration or
filing with, any governmental or regulatory authority is required on the part of
the Company in connection with the execution and delivery of this Agreement and
each of the Collateral Agreements, and the consummation of the transactions
contemplated hereby and thereby (including, without limitation, the offer,
issue, sale and delivery of the Securities and the Warrant Shares issuable upon
exercise of the Warrants), except such filings as shall have been made or
consents or approvals obtained prior to and which shall be effective on and as
of the Closing.  Based in part on the representations made by Buyer in ARTICLE V
of this Agreement, the offer and sale of the Securities to Buyer will be in
compliance with applicable federal and state securities laws.

               4.6  LITIGATION.  Except as set forth in the Company SEC Reports,
there are no material actions, suits, proceedings or investigations, either at
law or in equity, or before any commission or other administrative authority in
any United States or foreign jurisdiction, of any kind now pending or, to the
best of the Company's knowledge, threatened or proposed involving the Company or
any of its properties or assets or which questions the validity or legality of
the transactions contemplated hereby, or to the Company's actual knowledge,
against its employees or consultants with respect to the Company's business.

               4.7  SEC FILINGS; FINANCIAL STATEMENTS.  (a)  The Company has
filed all forms, reports and documents required to be filed with the Commission
since April 1, 1993 (collectively, the "COMPANY SEC REPORTS").  The Company SEC
Reports (i) were prepared in all material respects in accordance with the
requirements of the Securities Act or the Exchange Act, as the case may be, and
(ii) did not at the time they were filed (or if amended or superseded by a
filing prior to the date of this Agreement, then on the date of such filing)
contain any untrue statement of a material fact or omit to state a material fact
required to be stated therein or necessary in order


                                          6




to make the statements therein, in the light of the circumstances under which
they were made, not misleading.

               (b)  Each of the financial statements (including, in each case,
any related notes thereto) contained in the Company SEC Reports was prepared in
accordance with generally accepted accounting principles applied on a consistent
basis throughout the periods involved (except as may be indicated in the notes
thereto), and each was complete and correct in all material respects and
presented fairly in all material respects presented the financial position of
the Company as at the respective dates thereof and the results of its operations
and cash flows for the periods indicated, except that the unaudited interim
financial statements were or are subject to normal and recurring year-end
adjustments which were not or are not expected to be material in amount.

               4.8  NO UNDISCLOSED LIABILITIES.  The Company does not have any
material liabilities (absolute, accrued, contingent or otherwise) except
liabilities (a) in the aggregate adequately provided for in the Company's
audited balance sheet (including any related notes thereto) for the fiscal year
ended December 31, 1995 included in the Company's  Annual Report on Form 10-K
for the fiscal year ended December 31, 1995 (the "1995 BALANCE SHEET"), or (b)
incurred since December 31, 1995 in the ordinary course of business.

               4.9  ABSENCE OF CHANGES.  Since December 31, 1995, there has been
no material adverse change in the financial condition, business, or assets of
the Company.

               4.10 INTELLECTUAL PROPERTY.

               (a)  To the best of the Company's knowledge, it has done nothing
to compromise the secrecy, confidentiality or value of any of its trade secrets,
know-how, inventions, prototypes, designs, processes or technical data required
to conduct its business as now conducted or as proposed to be conducted.  The
Company will continue to take reasonable security measures in the future, as it
presently is doing, to protect the secrecy, confidentiality, and value of all of
its trade secrets, know-how, inventions, prototypes, designs, processes, and
technical data important to the conduct of its business.

               (b)  Except as set forth in the Company SEC Reports, the Company
has not granted rights to manufacture, produce, license, market or sell its
products to any other Person and is not bound by any agreement that affects the
Company's exclusive right to develop, manufacture, distribute, market or sell
its products.


                                          7



               4.11 NO DEFAULTS.  The Company is not in default (a) under its
Restated Certificate of Incorporation or Bylaws, each as amended or restated to
date, or any indenture, mortgage, lease agreement, contract, purchase order or
other instrument to which it is a party or by which it or any of its property is
bound or affected or (b) with respect to any order, writ, injunction or decree
of any court of any federal, state, municipal or other governmental department,
commission, board, bureau, agency or instrumentality, domestic or foreign, which
defaults, either singly or in the aggregate, would have a material adverse
effect on the Company.  At the time of the Closing, to the best knowledge of the
Company, there will exist no condition, event or act which constitutes, or which
after notice, lapse of time or both would constitute, a material default under
any of the foregoing which, either singly or in the aggregate, would have a
material adverse effect on the Company.

               4.12 OFFERINGS.  Except as contemplated by this Agreement or the
Company's 1990 Amended and Restated Long-Term Incentive Plan or as otherwise
disclosed by the Company to Buyer, the Company does not have any current plans
or intentions to issue any shares of its capital stock or any other securities
or any securities convertible or exchangeable into shares of its capital stock
or any other securities.

               4.13 BROKERS.  No broker, finder or investment banker  is
entitled to any brokerage, finder's or other fee or commission in connection
with the transactions contemplated by this Agreement based upon arrangements
made by or on behalf of the Company.

               4.14 CLINICAL TRIALS.  The Company is not aware of any non-public
information in the possession of its executive officers relating to the
completed or ongoing clinical trials of BDNF and/or NT3 that would be likely to
materially affect the price of the Common Stock.


                                      ARTICLE V

                       REPRESENTATIONS AND WARRANTIES OF BUYER

               Buyer hereby represents and warrants to the Company as of the
date hereof as follows:

               5.1  INVESTMENT.  Buyer is acquiring the Securities, and the
Warrant Shares into which the Warrants may be exercised, for its own account
(and not for the account of others) for investment and not with a view to, or
for sale in connection with, any distribution thereof, nor with any present
intention of distributing or selling


                                          8



the same; and, except as contemplated by this Agreement, Buyer has no present or
contemplated agreement, undertaking, arrangement, obligation, indebtedness or
commitment providing for the disposition thereof.

               5.2  AUTHORITY.  Buyer has full power and authority to execute
and deliver and to perform this Agreement and each of the Collateral Agreements
in accordance with their respective terms.  Buyer represents that it has not
been organized, reorganized or recapitalized specifically for the purpose of
investing in the Company.

               5.3  ACCREDITED INVESTOR.  Buyer is an Accredited Investor within
the definition set forth in Securities Act Rule 501(a).

               5.4  BROKERS.  No broker, finder or investment banker (other than
CS First Boston, the fees and expenses of whom will be paid by Buyer) is
entitled to any brokerage, finder's or other fee or commission in connection
with the transactions contemplated by this Agreement based upon arrangements
made by or on behalf of Buyer.

               5.5  CLINICAL TRIALS.  Buyer is not aware of any non-public
information in possession of its executive officers relating to the completed or
ongoing clinical trials of BDNF and/or NT3 that would be likely to materially
affect the price of the Common Stock.


                                      ARTICLE VI

                                   INDEMNIFICATION

               6.1  SURVIVAL OF REPRESENTATIONS, ETC.  All representations and
warranties contained herein shall survive the execution and delivery of this
Agreement and the Collateral Agreements and the closing of the transactions
contemplated hereby and thereby until the third anniversary of the date of this
Agreement (or until final resolution of any claim or action arising from the
untruth, inaccuracy or breach of any such representation and warranty, if notice
of such untruth, inaccuracy or breach was given prior to such third anniversary)
without regard to any investigation made by any of the parties hereto.  All
statements contained in any certificate or other instrument delivered by the
Company pursuant to this Agreement and denominated as representations and
warranties shall constitute representations and warranties by the Company under
this Agreement.  All agreements and covenants contained herein shall survive
indefinitely until, by their respective terms, they are no longer operative.


                                          9



               6.2  INDEMNIFICATION.  The Company shall, with respect to the
representations, warranties, covenants and agreements made by the Company herein
or in certificates or other instruments delivered in connection therewith,
indemnify, defend and hold Buyer harmless against all liability, together with
all reasonable costs and expenses related thereto (including legal and
accounting fees and expenses), arising from the untruth, inaccuracy or breach of
any such representations, warranties, covenants or agreements of the Company.


                                     ARTICLE VII

                                    MISCELLANEOUS

               7.1  LEGEND.  (a)  Each certificate representing Shares sold
pursuant to the provisions hereof, if deemed advisable by the Company, shall
bear the following legends:

               "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
          REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT
          BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED
          UNLESS AND UNTIL SUCH SHARES ARE REGISTERED UNDER SUCH ACT OR AN
          OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE COMPANY IS OBTAINED
          TO THE EFFECT THAT SUCH REGISTRATION IS NOT REQUIRED."

               (b)  Buyer hereby agrees not to offer, sell or otherwise transfer
the Shares in violation of the foregoing legend.

               7.2  ASSIGNMENT.  Neither this Agreement nor any of the rights or
obligations hereunder may be assigned by the Company without the prior written
consent of Buyer, or by Buyer without the prior written consent of the Company,
except that Buyer may, without such consent, assign the right to acquire the
Securities to a wholly-owned subsidiary or subsidiaries of Buyer, each of which
shall become parties to this Agreement and each of the Collateral Agreements;
provided, however, that Buyer shall continue to be a party to this Agreement and
to be bound by the provisions hereof.  Subject to the foregoing, this Agreement
shall be binding upon and inure to the benefit of the parties hereto and their
respective successors and assigns, and no other Person shall have any right,
benefit or obligation hereunder.

               7.3  NOTICES.  Unless otherwise provided herein, any notice,
request, instruction or other document to be given hereunder by any party to the
others shall be


                                          10



in writing and delivered in person or by courier, telegraphed, telexed or by
facsimile transmission (with receipt confirmed) or mailed by certified mail,
postage prepaid, return receipt requested (such mailed notice to be effective on
the date of such receipt is acknowledged), as follows:

          If to the Company:

                    Regeneron Pharmaceuticals, Inc.
                    777 Old Saw Mill River Road
                    Tarrytown, New York 10591-6707
                    Attn: Corporate Secretary
                    Telecopy No.: (914) 345-7721

          With a copy to:

                    Skadden, Arps, Slate, Meagher & Flom
                    919 Third Avenue
                    New York, New York  10022
                    Attn: Morris J. Kramer, Esq. and Matthew J. Mallow, Esq.
                    Telecopy No.: (212) 735-2000

          If to Buyer:

                    Amgen Inc.
                    Amgen Center
                    1840 DeHavilland Drive
                    Thousand Oaks, California 91320
                    Attn: The Corporate Secretary
                    Telecopy No.: (805) 499-9315

          With a copy to:

                    Latham & Watkins
                    633 West Fifth Street, Suite 4000
                    Los Angeles, California 90071
                    Attn: Michael W. Sturrock, Esq.
                    Telecopy No.: (213) 891-8763

or to such other place and with such other copies as either party may designate
as to itself by written notice to the others.


                                          11



               7.4  CHOICE OF LAW.  This Agreement shall be construed,
interpreted and the rights of the parties determined in accordance with the laws
of the State of New York except with respect to matters of law concerning the
internal corporate affairs of any corporate entity which is a party to or the
subject of this Agreement, and as to those matters the law of the jurisdiction
under which the respective entity derives its powers shall govern.

               7.5  ENTIRE AGREEMENT; AMENDMENTS AND WAIVERS.  This Agreement,
together with the Collateral Agreements, constitutes the entire agreement among
the parties pertaining to the subject matter hereof and thereof and supersedes
all prior agreements, understandings, negotiations and discussions, whether oral
or written, of the parties.  No supplement, modification or waiver of this
Agreement shall be binding unless executed in writing by the party to be bound
thereby.  No waiver of any of the provisions of this Agreement shall be deemed
or shall constitute a waiver of any other provision hereof (whether or not
similar), nor shall such waiver constitute a continuing waiver unless otherwise
expressly provided.

               7.6  COUNTERPARTS.  This Agreement may be executed in one or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

               7.7  INVALIDITY.  In the event that any one or more of the
provisions contained in this Agreement or in any other instrument referred to
herein, shall, for any reason, be held to be invalid, illegal or unenforceable
in any respect, such invalidity, illegality or unenforceability shall not affect
any other provision of this Agreement or any other such instrument.

               7.8  HEADINGS.  The headings of the Articles and Sections herein
are inserted for convenience of reference only and are not intended to be a part
of or to affect the meaning or interpretation of this Agreement.

               7.9 EXPENSES.  Each of the Company and Buyer will each be liable
for its own costs and expenses incurred in connection with the negotiation,
preparation, execution and performance of this Agreement, provided that the
Company will pay all stamp or similar taxes which may be payable (i) in
connection with the execution and delivery of this Agreement and each of the
Collateral Agreements (and any amendments or modifications thereto), and (ii) in
respect of the issuance of the Securities (including the issuance of the Warrant
Shares upon exercise of the Warrants) to Buyer.

               7.10 PUBLICITY.  Except for the initial press relating to the
execution and delivery of this Agreement (the form of which has been agreed to
by the parties hereto


                                          12



and is attached hereto as Exhibit A), neither party shall issue any press
release or make any public statement regarding the transactions contemplated
hereby, without prior consultation with the other party.

               7.11 SPECIFIC ENFORCEMENT.  The Company and Buyer acknowledge and
agree that if any of the provisions of this Agreement were not performed in
accordance with their specific terms or were otherwise breached, irreparable
damage would occur and it would be extremely impracticable and difficult to
measure damages.  Accordingly, in addition to any other rights and remedies to
which the parties may be entitled by law or equity, the parties shall be
entitled to an injunction or injunctions to prevent or cure breached of the
provisions of this Agreement and to enforce specifically the terms and
provisions hereof, and the parties expressly waive (i) the defense that a remedy
in damages will be adequate and (ii) any requirement, in an action for specific
performance, for the posting of a bond.

               7.12 FURTHER ASSURANCES.  On and after the date hereof, the
Company and Buyer will take all appropriate action and execute all documents,
instruments or conveyances of any kind which may be reasonably necessary or
advisable to carry out any of the provisions hereof.

               7.13 SECTION 912 OF THE NEW YORK BUSINESS CORPORATION LAW.  (a)
It is the intent of the parties that neither the approval by the Board of
Directors of the Company of the transactions contemplated by this Agreement and
the Collateral Agreements nor any other action taken or omitted to be taken by
the Board of Directors of the Company in connection with the transactions
contemplated by the foregoing agreements shall be deemed to be approval of Buyer
becoming an "interested shareholder" by the Board of Directors of the Company
under Section 912 of the New York Business Corporation Law.

               (b)  Buyer hereby represents and warrants to the Company as of
the date hereof that other than the Shares, Warrants and Warrant Shares to be
acquired under this Agreement and the Warrant Agreement, Buyer beneficially owns
and has the right to acquire (whether such right is exercisable immediately or
only after the passage of time) pursuant to any agreement, arrangement or
understanding (whether or not in writing) or upon the exercise of conversion
rights, exchange rights, warrants or options, 788,766 shares of Class A Common
Stock and 1,438,766 shares of Common Stock (which includes 788,766 shares of
Common Stock issuable if and when the shares of Class A Common Stock are
converted into shares of Common Stock).

                              [Signature Page to follow]


                                          13



               IN WITNESS WHEREOF, the parties hereto have executed this
Agreement, or have caused this Agreement to be duly executed on their respective
behalf by their respective officers thereunto duly authorized, as of the day and
year first above written.


                                        AMGEN INC.


                                        By
                                           -----------------------
                                        Name:
                                        Title:


                                        REGENERON PHARMACEUTICALS, INC.


                                        By
                                           -----------------------
                                        Name:
                                        Title:


                                         S-1




- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------





                                  WARRANT AGREEMENT



                                    BY AND BETWEEN

                           REGENERON PHARMACEUTICALS, INC.

                                         and

                                      AMGEN INC.



                              Dated as of April 15, 1996





- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------



                                  TABLE OF CONTENTS


                                                                            PAGE


SECTION 1.    Warrant Certificates..........................................  1

SECTION 2.    Execution of Warrant Certificates.............................  1

SECTION 3.    Registration..................................................  1

SECTION 4.    Registration of Transfers and Exchanges.......................  1

SECTION 5.    Warrants; Exercise of Warrant.................................  2

SECTION 6.    Payment of Taxes..............................................  3

SECTION 7.    Mutilated or Missing Warrant Certificates.....................  3

SECTION 8.    Reservation of Warrant Shares.................................  4

SECTION 9.    Obtaining Stock Exchange Listings.............................  4

SECTION 10.   Adjustment of Exercise Price and Number of Warrant Shares
               Issuable.....................................................  4

    (a)  Adjustment for Change in Capital Stock.............................  5
    (b)  Adjustment for Rights Issue........................................  6
    (c)  Adjustment for Other Distributions.................................  7
    (d)  Adjustment for Common Stock Issue..................................  7
    (e)  Adjustment for Convertible Securities Issue........................  9
    (f)  Current Market Price............................................... 10
    (g)  Consideration Received............................................. 10
    (h)  When De Minimis Adjustment May Be Deferred......................... 11
    (i)  When No Adjustment Required........................................ 11
    (j)  Notice of Adjustment............................................... 11
    (k)  Voluntary Reduction................................................ 11
    (l)  Reorganization of Company.......................................... 12
    (m)  Company Determination Final........................................ 13
    (n)  When Issuance or Payment May Be Deferred........................... 13
    (o)  Adjustment in Number of Shares..................................... 13
    (p)  Form of Warrants................................................... 14

SECTION 11.   Fractional Interests.......................................... 14

SECTION 12.   Notices to Warrant holders.................................... 14


                                          i



SECTION 13.   Notices to Company and Warrant Holder......................... 15

SECTION 14.   Supplements and Amendments.................................... 16

SECTION 15.   Successors.................................................... 16

SECTION 16.   Termination................................................... 17

SECTION 17.   Governing Law................................................. 17

SECTION 18.   Benefits of This Agreement.................................... 17

SECTION 19.   Counterparts.................................................. 17

EXHIBIT A..................................................................  A-1


                                          ii



              THIS WARRANT AGREEMENT (the "AGREEMENT") is dated as of April 15,
1996 and entered into by and between REGENERON PHARMACEUTICALS, INC., a New York
corporation (the "COMPANY"), and AMGEN INC., a Delaware corporation ("AMGEN").

              WHEREAS, the Company proposes to issue to Amgen, or its designee,
Common Stock Purchase Warrants, as hereinafter described (the "WARRANTS"), to
purchase up to an aggregate of 700,000 shares of Common Stock, $.001 par value
(the "COMMON STOCK"), of the Company (the Common Stock issuable on exercise of
the Warrants being referred to herein as the "WARRANT SHARES"), pursuant to a
Stock and Warrant Purchase Agreement dated as of the date hereof (the "PURCHASE
AGREEMENT").

              NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein set forth, the parties hereto agree as follows:

              SECTION 1.  WARRANT CERTIFICATES.  The certificates evidencing
the Warrants (the "WARRANT CERTIFICATES") to be delivered pursuant to this
Agreement shall be in registered form only and shall be substantially in the
form set forth in EXHIBIT A attached hereto.

              SECTION 2.  EXECUTION OF WARRANT CERTIFICATES.  Warrant
Certificates shall be signed on behalf of the Company by its Chairman of the
Board or its President or a Vice President and by its Secretary or an Assistant
Secretary under its corporate seal.  Each such signature upon the Warrant
Certificates may be in the form of a facsimile signature of the present or any
future Chairman of the Board, President, Vice President, Secretary or Assistant
Secretary and may be imprinted or otherwise reproduced on the Warrant
Certificates and for that purpose the Company may adopt and use the facsimile
signature of any person who shall have been Chairman of the Board, President,
Vice President, Secretary or Assistant Secretary, notwithstanding the fact that
at the time the Warrant Certificates shall be delivered or disposed of he shall
have ceased to hold such office.  The seal of the Company may be in the form of
a facsimile thereof and may be impressed, affixed, imprinted or otherwise
reproduced on the Warrant Certificates.

              In case any officer of the Company who shall have signed any of
the Warrant Certificates shall cease to be such officer before the Warrant
Certificates so signed shall have been disposed of by the Company, such Warrant
Certificates nevertheless may be delivered or disposed of as though such person
had not ceased to be such officer of the Company; and any Warrant Certificate
may be signed on behalf of the Company by any person who, at the actual date of
the execution of such Warrant Certificate, shall be a proper officer of the
Company to sign such Warrant Certificate, although at the date of the execution
of this Warrant Agreement any such person was not such officer.

              SECTION 3.  REGISTRATION.  The Company shall number and register
the Warrant Certificates in a register as they are issued.

              SECTION 4.  REGISTRATION OF TRANSFERS AND EXCHANGES.  The Company
shall from time to time register the transfer of any outstanding Warrant
Certificates in a Warrant register to be maintained by the Company upon
surrender of such Warrant Certificates accompanied by


                                          1



a written instrument or instruments of transfer in form satisfactory to the
Company, duly executed by the registered holder or holders thereof or by the
duly appointed legal representative thereof or by a duly authorized attorney.
Upon any such registration of transfer, a new Warrant Certificate shall be
issued to the transferee(s) and the surrendered Warrant Certificate shall be
cancelled and disposed of by the Company.

              The Warrant holders agree that each certificate representing
Warrant Shares will bear the following legend:

              "THIS WARRANT AND THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE
              NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
              AND MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR
              HYPOTHECATED UNLESS AND UNTIL, IN THE CASE OF THE SHARES, SUCH
              SHARES ARE REGISTERED UNDER SUCH ACT OR, IN THE CASE OF THIS
              WARRANT AND THE SHARES, AN OPINION OF COUNSEL REASONABLY
              SATISFACTORY TO THE COMPANY IS OBTAINED TO THE EFFECT THAT SUCH
              REGISTRATION IS NOT REQUIRED."

              The Warrant holders further agree that they shall not offer, sell
or otherwise transfer the Warrants or Warrant Shares in violation of the
foregoing legend.

              Warrant Certificates may be exchanged at the option of the
holder(s) thereof, when surrendered to the Company at its office for another
Warrant Certificate or other Warrant Certificates of like tenor and representing
in the aggregate a like number of Warrants.  Warrant Certificates surrendered
for exchange shall be cancelled and disposed of by the Company.

              SECTION 5.  WARRANTS; EXERCISE OF WARRANTS.  Subject to the terms
of this Agreement, each holder of Warrants shall have the right, which may be
exercised commencing at the opening of business on April 16, 1996 and until 5:00
p.m., New York time on April 15, 2001, to receive from the Company the number of
fully paid and nonassessable Warrant Shares which the holder may at the time be
entitled to receive on exercise of such Warrants and payment to the Company of
the Exercise Price (as defined below) then in effect for such Warrant Shares.
Each Warrant not exercised prior to 5:00 p.m., New York time, on April 15, 2001
shall become void and all rights thereunder and all rights in respect thereof
under this Agreement shall cease as of such time.

              A Warrant may be exercised upon surrender to the Company at its
office designated for such purpose (the address of which is set forth in SECTION
13 hereof) of the certificate or certificates evidencing the Warrants to be
exercised with the form of election to purchase duly filled in and signed, which
signature shall be guaranteed by a bank or trust company having an office or
correspondent in the United States or a broker or dealer which is a member of a
registered securities exchange or the National Association of Securities
Dealers, Inc., and upon payment to the Company of the exercise price (the
"EXERCISE PRICE") which is set forth in the form of Warrant Certificate attached
hereto as EXHIBIT A, subject to adjustment pursuant to SECTION 10, for the
number of Warrant Shares in respect of which such Warrants are


                                          2



then exercised.  Payment of the aggregate Exercise Price shall be made in cash
or by certified or official bank check payable to the order of the Company.

              Subject to the provisions of SECTION 6 hereof, upon such
surrender of Warrants and payment of the Exercise Price the Company shall issue
and cause to be delivered with all reasonable dispatch to or upon the written
order of the holder and in such name or names as the Warrant holder may
designate, a certificate or certificates for the number of full Warrant Shares
issuable upon the exercise of such Warrants together with cash as provided in
SECTION 11; PROVIDED, HOWEVER, that if any reclassification, consolidation,
merger or lease or sale of assets is proposed to be effected by the Company as
described in subsection (l) of SECTION 10 hereof, or a tender offer or an
exchange offer for shares of Common Stock of the Company shall be made, upon
such surrender of Warrants and payment of the Exercise Price as aforesaid, the
Company shall, as soon as possible, but in any event not later than two business
days thereafter, issue and cause to be delivered the full number of Warrant
Shares issuable upon the exercise of such Warrants in the manner described in
this sentence together with cash as provided in SECTION 11.  Such certificate or
certificates shall be deemed to have been issued and any person so designated to
be named therein shall be deemed to have become a holder of record of such
Warrant Shares as of the date of the surrender of such Warrants and payment of
the Exercise Price.

              The Warrants shall be exercisable, at the election of the holders
thereof, either in full or from time to time in part and, in the event that a
certificate evidencing Warrants is exercised in respect of fewer than all of the
Warrant Shares issuable on such exercise at any time prior to the date of
expiration of the Warrants, a new certificate evidencing the remaining Warrant
or Warrants will be issued and delivered pursuant to the provisions of this
Section and of SECTION 2 hereof.

              All Warrant Certificates surrendered upon exercise of Warrants
shall be cancelled and disposed of by the Company.  The Company shall keep
copies of this Agreement and any notices given or received hereunder available
for inspection by the holders during normal business hours at its office.

              SECTION 6.  PAYMENT OF TAXES.  The Company will pay all
documentary stamp taxes, if any, attributable to the initial issuance of Warrant
Shares upon the exercise of Warrants.

              SECTION 7.  MUTILATED OR MISSING WARRANT CERTIFICATES.  In case
any of the Warrant Certificates shall be mutilated, lost, stolen or destroyed,
the Company may in its discretion issue, in exchange and substitution for and
upon cancellation of the mutilated Warrant Certificate, or in lieu of and
substitution for the Warrant Certificate lost, stolen or destroyed, a new
Warrant Certificate of like tenor and representing an equivalent number of
Warrants, but only upon receipt of evidence reasonably satisfactory to the
Company of such loss, theft or destruction of such Warrant Certificate and
indemnity, if requested, also reasonably satisfactory to it.  Applicants for
such substitute Warrant Certificates shall also comply with such other
reasonable regulations and pay such other reasonable charges as the Company may
prescribe.


                                          3



              SECTION 8.  RESERVATION OF WARRANT SHARES.  The Company will at
all times reserve and keep available, free from preemptive rights, out of the
aggregate of its authorized but unissued Common Stock or its authorized and
issued Common Stock held in its treasury, for the purpose of enabling it to
satisfy any obligation to issue Warrant Shares upon exercise of the Warrants,
the maximum number of shares of Common Stock which may then be deliverable upon
the exercise of all the outstanding Warrants.

              The Company or, if appointed, the transfer agent for the Common
Stock (the "TRANSFER AGENT") and every subsequent transfer agent for any shares
of the Company's capital stock issuable upon the exercise of any of the rights
of purchase aforesaid will be irrevocably authorized and directed at all times
to reserve such number of authorized shares as shall be required for such
purpose.  The Company will keep a copy of this Agreement on file with the
Transfer Agent and with every subsequent transfer agent for any shares of the
Company's capital stock issuable upon the exercise of the rights of purchase
represented by the Warrants.  The Company will furnish such Transfer Agent a
copy of all notices of adjustments and certificates related thereto, transmitted
to each holder pursuant to SECTION 12 hereof.

              Before taking any action which would cause an adjustment pursuant
to SECTION 10 hereof to reduce the Exercise Price below the then par value (if
any) of the Warrant Shares, the Company will take any corporate action which
may, in the opinion of its counsel, be necessary in order that the Company may
validly and legally issue fully paid and nonassessable Warrant Shares at the
Exercise Price as so adjusted.

              The Company covenants that all Warrant Shares which may be issued
upon exercise of Warrants will, upon issue, be fully paid, nonassessable, free
of preemptive rights and free from all documentary stamp taxes, liens, charges
and security interests with respect to the issue thereof.

              SECTION 9.  OBTAINING STOCK EXCHANGE LISTINGS.  The Company will
from time to time take all action which may be necessary so that the Warrant
Shares, immediately upon their issuance upon the exercise of Warrants, will be
listed on the principal securities exchanges and markets within the United
States of America, if any, on which other shares of Common Stock are then
listed.

              SECTION 10.  ADJUSTMENT OF EXERCISE PRICE AND NUMBER OF WARRANT 
SHARES ISSUABLE.  The Exercise Price and the number of Warrant Shares issuable
upon the exercise of each Warrant are subject to adjustment from time to time 
upon the occurrence of the events enumerated in this SECTION 10.  For purposes
of this SECTION 10, "COMMON STOCK" means shares now or hereafter authorized 
of any class of common stock of the Company and any other stock of the Company,
however designated, that has the right (subject to any prior rights of any 
class or series of preferred stock) to participate in any distribution of
the assets or earnings of the Company without limit as to per share amount,
including, without limitation, the Class A Common Stock, par value $.001, of the
Company.


                                          4



                   ADJUSTMENT FOR CHANGE IN CAPITAL STOCK.

                   If the Company:

                   1.   pays a dividend or makes a distribution on its Common
              Stock in shares of its Common Stock;

                   2.   subdivides its outstanding shares of Common Stock into
              a greater number of shares; or

                   3.   combines its outstanding shares of Common Stock into a
              smaller number of shares;

then the Exercise Price in effect immediately prior to such action shall then be
adjusted in accordance with the formula:

                        1      O
                       E = E x -
                               A

Where:
          1
         E =  the adjusted Exercise Price

         E =  the current Exercise Price

         O =  the number of shares of Common Stock outstanding prior to such
              action

         A =  the number of shares of Common Stock outstanding immediately
              after such action


              In the case of a dividend or distribution the adjustment shall
become effective immediately after the record date for determination of holders
of shares of Common Stock entitled to receive such dividend or distribution, and
in the case of a subdivision or combination, the adjustment shall become
effective immediately after the effective date of such corporate action.

              If after an adjustment a holder of a Warrant upon exercise of it
may receive shares of two or more classes of capital stock of the Company, the
Company shall determine the allocation of the adjusted Exercise Price between
the classes of capital stock.  After such allocation, the exercise privilege,
the number of shares issuable upon such exercise, and the Exercise Price of each
class of capital stock shall thereafter be subject to adjustment on terms
comparable to those applicable to Common Stock in this Section 10.


                                          5



              Such adjustment shall be made successively whenever any event
listed above shall occur.

         (b)  ADJUSTMENT FOR RIGHTS ISSUE.

              If the Company distributes any rights, options or warrants to all
holders of its Common Stock entitling them at any time after the record date
mentioned below to purchase shares of Common Stock at a price per share less
than the Current Market Price (as defined in SECTION 10(f)) per share of Common
Stock on that record date, the Exercise Price shall be adjusted in accordance
with the formula:

                                N x P
                            O + -----
                        1         M
                       E  = E x -----
                                O + N


where:
           1
         E  = the adjusted Exercise Price.

         E  = the current Exercise Price.

         O  = the number of shares of Common Stock outstanding on the record
              date.

         N  = the number of additional shares of Common Stock issuable upon
              exercise of the rights, options or warrants offered.

         P  = the exercise price per share of the additional shares issuable
              upon exercise of the rights, options or warrants.

         M  = the Current Market Price per share of Common Stock on the record
              date.

              The adjustment shall be made successively whenever any such
rights, options or warrants are issued and shall become effective immediately
after the record date for the determination of stockholders entitled to receive
the rights, options or warrants.  If at the end of the period during which such
rights, options or warrants are exercisable, not all rights, options or warrants
shall have been exercised, the Exercise Price shall be immediately readjusted to
what it would have been if "N" in the above formula had been the number of
shares actually issued.


                                          6



         (c)  ADJUSTMENT FOR OTHER DISTRIBUTIONS.

              If the Company distributes to all holders of its Common Stock any
of its assets (including but not limited to securities and cash), debt
securities, capital stock, or any rights or warrants to purchase assets, debt
securities, capital stock, or other securities of the Company, the Exercise
Price shall be adjusted in accordance with the formula:

                         1       M - F
                        E  = E x -----
                                   M

where:
           1
         E  = the adjusted Exercise Price.

         E  = the current Exercise Price.

         M  = the Current Market Price per share of Common Stock on the record
              date mentioned below.

         F  = the fair market value on the record date of the assets, debt
              securities, capital stock or rights or warrants applicable to one
              share of Common Stock.  The Board of Directors shall determine
              the fair market value.

              The adjustment shall be made successively whenever any such
distribution is made and shall become effective immediately after the record
date for the determination of stockholders entitled to receive the distribution.

              This subsection does not apply to (i) dividends, distributions,
combinations or issuances referred to in subsection (a) of this SECTION 10, (ii)
rights, options or warrants referred to in subsection (b) of this SECTION 10, or
(iii) non-extraordinary quarterly cash dividends distributed to all holders of
Common Stock.

         (d)  ADJUSTMENT FOR COMMON STOCK ISSUE.

              If the Company issues shares of Common Stock for a consideration
per share less than the Current Market Price per share of Common Stock on the
date the Company fixes the offering price of such additional shares, the
Exercise Price shall be adjusted in accordance with the formula:


                                          7



                                       P
                                  O + ---
                          1            M
                         E  = E x -------
                                     A

where:

           1
         E  = the adjusted Exercise Price.

         E  = the then current Exercise Price.

         O  = the number of shares outstanding immediately prior to the
              issuance of such additional shares.

         P  = the aggregate consideration received for the issuance of such
              additional shares.

         M  = the Current Market Price per share of Common Stock on the date of
              issuance of such additional shares.

         A  = the number of shares outstanding immediately after the issuance
              of such additional shares.

              The adjustment shall be made successively whenever any such
issuance is made, and shall become effective immediately after such issuance.

              This subsection (d) does not apply to:

              (1)     the exercise of Warrants,

              (2)     rights, options, warrants or other distributions referred
         to in subsections (b), (c) or (e) of this SECTION 10,

              (3)     Common Stock issued to the Company's directors, employees
         and non-employee service providers under bona fide benefit plans
         adopted by the Board of Directors and approved by the holders of
         Common Stock when required by law, if such Common Stock would
         otherwise be covered by this subsection (d), or

              (4)     Common Stock issued in a bona fide public offering
         pursuant to a firm commitment underwriting.

              (5)     issuances of shares of Common Stock for a consideration
         per share less than 100%,  but greater than 92%, of the Current Market
         Price per share of Common Stock on the date the Company fixes the
         offering price of such additional shares.


                                          8



         (e)  ADJUSTMENT FOR CONVERTIBLE SECURITIES ISSUE.

              If the Company issues any securities convertible into or
exchangeable for Common Stock (other than securities issued in transactions
described in subsections (b) and (c) of this SECTION 10) for a consideration per
share of Common Stock initially deliverable upon conversion or exchange of such
securities less than the Current Market Price per share of Common Stock on the
date of issuance of such securities, the Exercise Price shall be adjusted in
accordance with this formula:

                                        P
                                  O + -----
                          1             M
                         E  = E x ---------
                                    O + D


where:
           1
         E  = the adjusted Exercise Price.

         E  = the then current Exercise Price.

         O  = the number of shares outstanding immediately prior to the
              issuance of such securities.

         P  = the aggregate consideration received for the issuance of such
              securities.

         M  = the Current Market Price per share of Common Stock on the date of
              issuance of such securities.

         D  = the maximum number of shares deliverable upon conversion or in
              exchange for such securities at the initial conversion or
              exchange rate.

              The adjustment shall be made successively whenever any such
issuance is made, and shall become effective immediately after such issuance.

              If all of the Common Stock deliverable upon conversion or
exchange of such securities have not been issued when such securities are no
longer outstanding, then the Exercise Price shall promptly be readjusted to the
Exercise Price which would then be in effect had the adjustment upon the
issuance of such securities been made on the basis of the actual number of
shares of Common Stock issued upon conversion or exchange of such securities.


                                          9



              This subsection (e) does not apply to convertible securities
issued in a bona fide public offering pursuant to a firm commitment
underwriting, nor does this subsection apply to issuances of any securities
convertible into or exchangeable for Common Stock for a consideration per share
of Common Stock initially deliverable upon conversion or exchange of such
securities less than 100%, but greater than 92%, of the Current Market Price per
share of Common Stock on the date of issuance of such securities.

         (f)  CURRENT MARKET PRICE.

              As used in this Agreement, the "Current Market Price" per share
of Common Stock on any date is the average of the Quoted Prices of the Common
Stock for 30 consecutive trading days commencing 45 trading days before the date
in question.  The "Quoted Price" of the Common Stock is the last reported sales
price of the Common Stock as reported by Nasdaq National Market, or if the
Common Stock is listed on a national securities exchange, the last reported
sales price of the Common Stock on such exchange (which shall be for
consolidated trading if applicable to such exchange), or if neither so reported
or listed, the last reported bid price of the Common Stock.  In the absence of
one or more such quotations, the Board of Directors of the Company shall
determine the Current Market Price on the basis of such quotations as it in good
faith considers appropriate.

         (g)  CONSIDERATION RECEIVED.

              For purposes of any computation respecting consideration received
pursuant to subsections (d) and (e) of this SECTION 10, the following shall
apply:

              (1)     in the case of the issuance of shares of Common Stock for
         cash, the consideration shall be the amount of such cash, provided
         that in no case shall any deduction be made for any commissions,
         discounts or other expenses incurred by the Company for any
         underwriting of the issue or otherwise in connection therewith;

              (2)     in the case of the issuance of shares of Common Stock for
         a consideration in whole or in part other than cash, the consideration
         other than cash shall be deemed to be the fair market value thereof as
         determined in good faith by the Board of Directors (irrespective of
         the accounting treatment thereof), whose determination shall be
         conclusive, and described in a Board resolution; and

              (3)     in the case of the issuance of securities convertible
         into or exchangeable for shares, the aggregate consideration received
         therefor shall be deemed to be the consideration received by the
         Company for the issuance of such securities plus the additional
         minimum consideration, if any, to be received by the Company upon the
         conversion or exchange thereof (the consideration in each case to be
         determined in the same manner as provided in clauses (1) and (2) of
         this subsection).


                                          10



         (h)  WHEN DE MINIMIS ADJUSTMENT MAY BE DEFERRED.

              No adjustment in the Exercise Price need be made unless the
adjustment would require an increase or decrease of at least 1% in the Exercise
Price.  Any adjustments that are not made shall be carried forward and taken
into account in any subsequent adjustment.

              All calculations under this Section shall be made to the nearest
cent or to the nearest 1/100th of a share, as the case may be.

         (i)  WHEN NO ADJUSTMENT REQUIRED.

              No adjustment need be made for a transaction referred to in
subsections (a), (b), (c), (d) or (e) of this SECTION 10 if Warrant holders are
to participate in the transaction on a basis and with notice that the Board of
Directors determines to be fair and appropriate in light of the basis and notice
on which holders of Common Stock participate in the transaction.

              No adjustment need be made for rights to purchase Common Stock
pursuant to a Company plan for reinvestment of dividends or interest.

              No adjustment need be made for a change in the par value or no
par value of the Common Stock.

              If the Company distributes or issues rights to all holders of its
Common Stock pursuant to a shareholder rights plan, then no adjustment shall be
made pursuant to this SECTION 10 upon such distribution or issuance if, upon
exercise of the Warrants, each holder thereof receives the same type and number
of unexpired rights it would have received (as adjusted for any event described
in SECTION 10(a) OR 10(l)) had it exercised its Warrants, and been a holder of
the Warrant Shares issuable upon exercise thereof, prior to the record date for
such distribution or issuance.

              To the extent Warrants become convertible into cash, no
adjustment need be made thereafter as to the cash.  Interest will not accrue on
the cash.

         (j)  NOTICE OF ADJUSTMENT.

              Whenever the Exercise Price is adjusted, the Company shall
provide the notices required by SECTION 12 hereof.

         (k)  VOLUNTARY REDUCTION.

              The Company from time to time may reduce the Exercise Price by
any amount for any period of time if the period is at least 20 days and if the
reduction is irrevocable during the period; PROVIDED, HOWEVER, that in no event
may the Exercise Price be less than the par value of a share of Common Stock.


                                          11



              Whenever the Exercise Price is reduced pursuant to SUBSECTION
10(k), the Company shall mail to Warrant holders a notice of the reduction.  The
Company shall mail the notice at least 15 days before the date the reduced
Exercise Price takes effect.  The notice shall state the reduced Exercise Price
and the period it will be in effect.

              A reduction of the Exercise Price does not change or adjust the
Exercise Price otherwise in effect for purposes of subsections (a), (b), (c),
(d) and (e) of this SECTION 10.

         (l)  REORGANIZATION OF COMPANY.

              If any reclassification of the Common Stock of the Company or any
consolidation or merger of the Company with another entity, or the sale or lease
of all or substantially all of the Company's assets to another entity shall be
effected in such a way that holders of the Common Stock of the Company shall be
entitled to receive stock, securities or assets with respect to or in exchange
for such Common Stock, then, as a condition precedent to such reclassification,
consolidation, merger, sale or lease, lawful and adequate provisions shall be
made whereby the Warrant holder shall thereafter have the right to purchase and
receive upon the basis and the terms and conditions specified in this Agreement
and in lieu of the shares of Common Stock immediately theretofore purchasable
and receivable upon the exercise of the rights represented hereby, such shares
of stock, securities or assets as may be issued or payable in such
reclassification, consolidation, merger, sale or lease with respect to or in
exchange for the number of shares of Common Stock purchasable and receivable
upon the exercise of the rights represented hereby had such rights been
exercised immediately prior thereto, and in any such case appropriate provision
shall be made with respect to the rights and interests of the holders of the
Warrants to the end that the provisions hereof (including without limitation
provisions for adjustments of the Exercise Price and of the number of shares of
Common Stock purchasable and receivable upon the exercise of the Warrant) shall
thereafter be applicable, as nearly as may be, in relation to any shares of
stock, securities or assets thereafter deliverable upon the exercise hereof.
The Company will not effect any such reclassification, consolidation, merger,
sale or lease, unless prior to the consummation thereof the successor
corporation (if other than the Company) resulting from such reclassification,
consolidation or merger or the corporation purchasing or leasing such assets
shall assume by a supplemental Warrant Agreement, executed and mailed or
delivered to the holders of the Warrants at the last address thereof appearing
on the books of Company, the obligation to deliver to such holders such shares
of stock, securities or assets as, in accordance with the foregoing provisions,
such holders may be entitled to purchase.

              If the issuer of securities deliverable upon exercise of Warrants
under the supplemental Warrant Agreement is an affiliate of the formed,
surviving, transferee or lessee corporation, that issuer shall join in the
supplemental Warrant Agreement.

              If this subsection (l) applies, subsections (a), (b), (c), (d)
and (e) of this SECTION 10 do not apply.


                                          12



         (m)  COMPANY DETERMINATION FINAL.

              Any determination that the Company or the Board of Directors must
make pursuant to this SECTION 10 is conclusive.

         (n)  WHEN ISSUANCE OR PAYMENT MAY BE DEFERRED.

              In any case in which this SECTION 10 shall require that an
adjustment in the Exercise Price be made effective as of a record date for a
specified event, the Company may elect to defer until the occurrence of such
event (i) issuing to the holder of any Warrant exercised after such record date
the Warrant Shares and other capital stock of the Company, if any, issuable upon
such exercise over and above the Warrant Shares and other capital stock of the
Company, if any, issuable upon such exercise on the basis of the Exercise Price
and (ii) paying to such holder any amount in cash in lieu of a fractional share
pursuant to SECTION 11; PROVIDED, HOWEVER, that the Company shall deliver to
such holder a due bill or other appropriate instrument evidencing such holder's
right to receive such additional Warrant Shares, other capital stock and cash
upon the occurrence of the event requiring such adjustment.

         (o)  ADJUSTMENT IN NUMBER OF SHARES.

              Upon each adjustment of the Exercise Price pursuant to this
SECTION 10, each Warrant outstanding prior to the making of the adjustment in
the Exercise Price shall thereafter evidence the right to receive upon payment
of the adjusted Exercise Price that number of shares of Common Stock (calculated
to the nearest hundredth) obtained from the following formula:

                                1        E
                               N  = N x ----
                                          1
                                         E

where:
           1
          N = the adjusted number of Warrant Shares issuable upon exercise of a
              Warrant by payment of the adjusted Exercise Price.

          N = the number of Warrant Shares previously issuable upon exercise of
              a Warrant by payment of the Exercise Price prior to adjustment.
           1
          E = the adjusted Exercise Price.

          E = the Exercise Price prior to adjustment.


                                          13



         (p)  FORM OF WARRANTS.

              Irrespective of any adjustments in the Exercise Price or the
number or kind of shares purchasable upon the exercise of the Warrants, Warrants
theretofore or thereafter issued may continue to express the same price and
number and kind of shares as are stated in the Warrants initially issuable
pursuant to this Agreement.

              SECTION 11.  FRACTIONAL INTERESTS.  The Company shall not be
required to issue fractional Warrant Shares on the exercise of Warrants.  If
more than one Warrant shall be presented for exercise in full at the same time
by the same holder, the number of full Warrant Shares which shall be issuable
upon the exercise thereof shall be computed on the basis of the aggregate number
of Warrant Shares purchasable on exercise of the Warrants so presented.  If any
fraction of a Warrant Share would, except for the provisions of this SECTION 11,
be issuable on the exercise of any Warrants (or specified portion thereof), the
Company shall pay an amount in cash equal to the Current Market Price on the day
immediately preceding the date the Warrant is presented for exercise, multiplied
by such fraction.

              SECTION 12.  NOTICES TO WARRANT HOLDERS.  Upon any adjustment of
the Exercise Price pursuant to SECTION 10, the Company shall promptly thereafter
(i) cause to be filed with the Company a certificate of a firm of independent
public accountants of recognized standing selected by the Board of Directors of
the Company (who may be the regular auditors of the Company) setting forth the
Exercise Price after such adjustment and setting forth in reasonable detail the
method of calculation and the facts upon which such calculations are based and
setting forth the number of Warrant Shares (or portion thereof) issuable after
such adjustment in the Exercise Price, upon exercise of a Warrant and payment of
the adjusted Exercise Price, which certificate shall be conclusive evidence of
the correctness of the matters set forth therein, and (ii) cause to be given to
each of the registered holders of the Warrant Certificates at his address
appearing on the Warrant register written notice of such adjustments by first-
class mail, postage prepaid.  Where appropriate, such notice may be given in
advance and included as a part of the notice required to be mailed under the
other provisions of this SECTION 12.

              In case:

              (a)     the Company shall authorize the issuance to all holders
         of shares of Common Stock of rights, options or warrants to subscribe
         for or purchase shares of Common Stock or of any other subscription
         rights or warrants; or

              (b)     the Company shall authorize the distribution to all
         holders of shares of Common Stock of evidences of its indebtedness or
         assets (other than cash dividends or cash distributions payable out of
         earnings or earned surplus or dividends or distributions payable in
         shares of Common Stock); or

              (c)     of any consolidation or merger to which the Company is a
         party and for which approval of any shareholders of the Company is
         required, or of the conveyance or transfer of all or substantially all
         of the properties and assets of the Company, or of


                                          14



         any reclassification or change of Common Stock issuable upon exercise 
         of the Warrants (other than a change in par value, or from par value to
         no par value, or from no par value to par value, or as a result of a 
         subdivision or combination), or a tender offer or exchange offer for 
         shares of Common Stock; or

              (d)     of the voluntary or involuntary dissolution, liquidation
         or winding up of the Company; or

              (e)     the Company proposes to take any action that would
         require an adjustment in the Exercise Price pursuant to subsections
         (a), (b), (c), (d) or (e) of SECTION 10 and if the Company does not
         arrange for Warrant holders to participate pursuant to subsection (i)
         of SECTION 10, or if the Company takes any action that would require a
         supplemental Warrant Agreement pursuant to subsection (l) of SECTION
         10,

then the Company shall cause to be given to each of the registered holders of
the Warrant Certificates at his address appearing on the Warrant register, at
least 20 days (or 10 days in any case specified in clauses (a), (b) or (c)
above) prior to the applicable record date hereinafter specified, or promptly in
the case of events for which there is no record date, by first-class mail,
postage prepaid, a written notice stating (i) the date as of which the holders
of record of shares of Common Stock to be entitled to receive any such rights,
options, warrants or distribution are to be determined, or (ii) the initial
expiration date set forth in any tender offer or exchange offer for shares of
Common Stock, or (iii) the date on which any such consolidation, merger,
conveyance, transfer, dissolution, liquidation or winding up is expected to
become effective or consummated, and the date as of which it is expected that
holders of record of shares of Common Stock shall be entitled to exchange such
shares for securities or other property, if any, deliverable upon such
reclassification, consolidation, merger, conveyance, transfer, dissolution,
liquidation or winding up.  The failure to give the notice required by this
SECTION 12 or any defect therein shall not affect the legality or validity of
any distribution, right, option, warrant, consolidation, merger, conveyance,
transfer, dissolution, liquidation or winding up, or the vote upon any action.

              Nothing contained in this Agreement or in any of the Warrant
Certificates shall be construed as conferring upon the holders thereof the right
to vote or to consent or to receive notice as shareholders in respect of the
meetings of shareholders or the election of Directors of the Company or any
other matter, or any rights whatsoever as shareholders of the Company.

              SECTION 13.  NOTICES TO COMPANY AND WARRANT HOLDER.  Unless
otherwise provided herein, any notice, request, instruction or other document to
be given hereunder by any party to the others shall be in writing and delivered
in person or by courier, telegraphed, telexed or by facsimile transmission (with
receipt confirmed), or mailed by certified mail, postage prepaid, return receipt
requested (such mailed notice to be effective on the date such receipt is
acknowledged), as follows:


                                          15




         If to the Company:

                      Regeneron Pharmaceuticals, Inc.
                      777 Old Saw Mill River Road
                      Tarrytown, New York 10591-6707
                      Attn: Corporate Secretary
                      Telecopy No.: (914) 345-7721

         With a copy to:

                      Skadden, Arps, Slate, Meagher & Flom
                      919 Third Avenue
                      New York, New York 10022
                      Attn: Morris Kramer, Esq.
                      Telecopy No.: (212) 735-2000

         If to Warrant Holder:

                      Amgen Inc.
                      Amgen Center
                      1840 DeHavilland Drive
                      Thousand Oaks, California 91320
                      Attn: The Corporate Secretary
                      Telecopy No.: (805) 499-9315

         With a copy to:

                      Latham & Watkins
                      633 West Fifth Street, Suite 4000
                      Los Angeles, California 90071
                      Attn: Michael W. Sturrock, Esq.
                      Telecopy No.: (213) 891-8763

or to such other place and with such other copies as either party may designate
as to itself by written notice to the others.

              SECTION 14.  SUPPLEMENTS AND AMENDMENTS.  The Company may not
supplement or amend this Agreement without the prior written approval of the
holders of Warrant Certificates affected by such supplement or amendment.

              SECTION 15.  SUCCESSORS.  All the covenants and provisions of
this Agreement by or for the benefit of the Company shall bind and inure to the
benefit of its respective successors and assigns hereunder.


                                          16



              SECTION 16.  TERMINATION.  This Agreement shall terminate at 5:00
p.m., New York time on April 15, 2001.  Notwithstanding the foregoing, this
Agreement will terminate on any earlier date if all Warrants have been
exercised.

              SECTION 17.  GOVERNING LAW.  This Agreement and each Warrant
Certificate issued hereunder shall be deemed to be a contract made under the
laws of the State of New York and for all purposes shall be construed in
accordance with the internal laws of said State.

              SECTION 18.  BENEFITS OF THIS AGREEMENT.  Nothing in this
Agreement shall be construed to give to any person or corporation other than the
Company and the registered holders of the Warrant Certificates any legal or
equitable right, remedy or claim under this Agreement; but this Agreement shall
be for the sole and exclusive benefit of the Company and the registered holders
of the Warrant Certificates.

              SECTION 19.  COUNTERPARTS.  This Agreement may be executed in any
number of counterparts and each of such counterparts shall for all purposes be
deemed to be an original, and all such counterparts shall together constitute
but one and the same instrument.

                              [Signature Page To Follow]


                                          17



              IN WITNESS WHEREOF, the parties hereto have caused this Agreement
to be duly executed, as of the day and year first above written.


                                       REGENERON PHARMACEUTICALS, INC.



                                       By:
                                             -----------------------------------

                                                 Name:  Leonard S. Schleifer
                                                 Title: President

- ------------------------------------
Seal




Attest:
         --------------------------
              Secretary


                                       AMGEN INC.



                                       By:
                                             -----------------------------------
                                            Name:
                                            Title:

- ------------------------------------
Seal




Attest:
         --------------------------
              Secretary


                                         S-1



                                                                       EXHIBIT A

                            [Form of Warrant Certificate]


THIS WARRANT AND THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE OFFERED,
SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS AND UNTIL, WITH
RESPECT TO THE SHARES, SUCH SHARES ARE REGISTERED UNDER SUCH ACT OR, WITH
RESPECT TO THIS WARRANT OR THE SHARES, AN OPINION OF COUNSEL REASONABLY
SATISFACTORY TO THE COMPANY IS OBTAINED TO THE EFFECT THAT SUCH REGISTRATION IS
NOT REQUIRED.

            EXERCISABLE ON OR BEFORE 5:00 P.M., NEW YORK TIME, APRIL 15, 2001

No.                                                             700,000 Warrants

                                 Warrant Certificate

                           REGENERON PHARMACEUTICALS, INC.

              This Warrant Certificate certifies that Amgen, Inc., or
registered assigns, is the registered holder of 700,000 Warrants expiring April
15, 2001 (the "WARRANTS") to purchase Common Stock, $.001 par value (the "COMMON
STOCK"), of REGENERON PHARMACEUTICALS, INC., a New York corporation (the
"COMPANY").  Each Warrant entitles the holder to receive from the Company upon
exercise on or before 5:00 p.m. New York Time on April 15, 2001, one fully paid
and nonassessable share of Common Stock (a "WARRANT SHARE") at the initial
exercise price (the "EXERCISE PRICE") of $16.00 payable in lawful money of the
United States of America upon surrender of this Warrant Certificate and payment
of the Exercise Price at the office of the Company designated for such purpose,
subject to the conditions set forth herein and in the Warrant Agreement referred
to herein.  The Exercise Price and number of Warrant Shares issuable upon
exercise of the Warrants are subject to adjustment upon the occurrence of
certain events set forth in the Warrant Agreement.

              No Warrant may be exercised after 5:00 p.m., New York Time on
April 15, 2001, and to the extent not exercised by such time such Warrants shall
become void.


                                         A-1



              The Warrants evidenced by this Warrant Certificate are issued
pursuant to a Warrant Agreement dated as of April 15, 1996 (the "WARRANT
AGREEMENT"), duly executed and delivered by the Company, which Warrant Agreement
is hereby incorporated by reference in and made a part of this instrument and is
hereby referred to for a description of the rights, limitation of rights,
obligations, duties and immunities thereunder of the Company and the holders
(the words "holders" or "holder" meaning the registered holders or registered
holder) of the Warrants.  A copy of the Warrant Agreement may be obtained by the
holder hereof upon written request to the Company.

              Warrants may be exercised at any time on or before 5:00 p.m., New
York time on April 15, 2001.  The holder of Warrants evidenced by this Warrant
Certificate may exercise them by surrendering this Warrant Certificate, with the
form of election to purchase set forth hereon properly completed and executed,
together with payment of the Exercise Price at the office of the Company
designated for such purpose.  In the event that upon any exercise of Warrants
evidenced hereby the number of Warrants exercised shall be less than the total
number of Warrants evidenced hereby, there shall be issued to the holder hereof
or his assignee a new Warrant Certificate evidencing the number of Warrants not
exercised.  No adjustment shall be made for any dividends on any Common Stock
issuable upon exercise of this Warrant.

              The Warrant Agreement provides that upon the occurrence of
certain events the Exercise Price set forth on the face hereof may, subject to
certain conditions, be adjusted.  If the Exercise Price is adjusted, the Warrant
Agreement provides that the number of shares of Common Stock issuable upon the
exercise of each Warrant shall be adjusted.  No fractions of a share of Common
Stock will be issued upon the exercise of any Warrant, but the Company will pay
the cash value thereof determined as provided in the Warrant Agreement.

              The holders of Warrants are entitled to certain registration
rights with respect to the Common Stock purchasable upon exercise thereof.  Said
registration rights are set forth in full in a Registration Rights Agreement
dated as of April 15, 1996, between the Company and Amgen.  A copy of the
Registration Rights Agreement may be obtained by the holder hereof upon written
request to the Company.

              Warrant Certificates, when surrendered at the office of the
Company by the registered holder thereof in person or by legal representative or
attorney duly authorized in writing, may be exchanged, in the manner and subject
to the limitations provided in the Warrant Agreement, but without payment of any
service charge, for another Warrant Certificate or Warrant Certificates of like
tenor evidencing in the aggregate a like number of Warrants.

              Upon due presentation for registration of transfer of this
Warrant Certificate at the office of the Company a new Warrant Certificate or
Warrant Certificates of like tenor and evidencing in the aggregate a like number
of Warrants shall be issued to the transferee(s) in exchange for this Warrant
Certificate, subject to the limitations provided in the Warrant Agreement,
without charge except for any tax or other governmental charge imposed in
connection therewith.


                                         A-2



              The Company may deem and treat the registered holder(s) thereof
as the absolute owner(s) of this Warrant Certificate (notwithstanding any
notation of ownership or other writing hereon made by anyone), for the purpose
of any exercise hereof, of any distribution to the holder(s) hereof, and for all
other purposes, and the Company shall not be affected by any notice to the
contrary.  Neither the Warrants nor this Warrant Certificate entitles any holder
hereof to any rights of a stockholder of the Company.

              This Warrant Certificate shall not be valid unless countersigned
by the Company, as such term is used in the Warrant Agreement.

              This Warrant Certificate shall not be offered, sold or otherwise
transferred in violation of the legend on the first page hereof.

                              [Signature Page To Follow]


                                         A-3



                 IN WITNESS WHEREOF, the Company has caused this Warrant
Certificate to be signed by its President and by its Secretary and has caused
its corporate seal to be affixed hereunto or imprinted hereon.

Dated:  April 15, 1996


                                     REGENERON PHARMACEUTICALS, INC.



                                     By:
                                             -----------------------------------
                                          Name:  Leonard S. Schleifer
                                          Title:  President



                                     By:
                                             -----------------------------------
                                          Name:  Paul Lubetkin
                                          Title:  Secretary


                                         S-1



                            [Form of Election to Purchase

                      (To Be Executed Upon Exercise Of Warrant)


               The undersigned hereby irrevocably elects to exercise the right,
represented by this Warrant Certificate, to receive _________ shares of Common
Stock and herewith tenders payment for such shares to the order of REGENERON
PHARMACEUTICALS, INC. in the amount of $_____ in accordance with the terms
hereof.  The undersigned requests that a certificate for such shares be
registered in the name of ________________, whose address is
_______________________________ and that such shares be delivered to
________________ whose address is _________________________________.  If said
number of shares is less than all of the shares of Common Stock purchasable
hereunder, the undersigned requests that a new Warrant Certificate representing
the remaining balance of such shares be registered in the name of
______________, whose address is  _________________________, and that such
Warrant Certificate be delivered to _________________, whose address is
__________________.


                                     Signature:
                                                   -----------------------------


Date:
      ------------------------


                                   Signature Guaranteed:
                                                            --------------------







- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------






                          REGISTRATION RIGHTS AGREEMENT


                                 BY AND BETWEEN

                         REGENERON PHARMACEUTICALS, INC.

                                       and

                                   AMGEN INC.


                           Dated as of April 15, 1996






- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------





                               TABLE OF CONTENTS*




SECTION 1.  Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . .   1

SECTION 2.  Securities Subject to this Agreement . . . . . . . . . . . . . .   2

     (a)    Registrable Securities . . . . . . . . . . . . . . . . . . . . .   2
     (b)    Holders of Registrable Securities. . . . . . . . . . . . . . . .   2

SECTION 3.  Demand Registrations . . . . . . . . . . . . . . . . . . . . . .   3

     (a)    Demand by Holders. . . . . . . . . . . . . . . . . . . . . . . .   3
     (b)    Effective Registration . . . . . . . . . . . . . . . . . . . . .   3
     (c)    Registration Statement Form. . . . . . . . . . . . . . . . . . .   4
     (d)    Selection of Underwriters. . . . . . . . . . . . . . . . . . . .   4
     (e)    Registration of Other Securities . . . . . . . . . . . . . . . .   4
     (f)    Priority Among Holders of Registrable Securities in Requested
            Registration . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     (g)    Delay of Requested Registration. . . . . . . . . . . . . . . . .   5

SECTION 4.  Piggyback Registrations. . . . . . . . . . . . . . . . . . . . .   5

     (a)    Participation. . . . . . . . . . . . . . . . . . . . . . . . . .   5
     (b)    Underwriter's Cutback. . . . . . . . . . . . . . . . . . . . . .   6
     (c)    No Effect on Demand Registrations. . . . . . . . . . . . . . . .   6

SECTION 5.  Hold-Back Agreements . . . . . . . . . . . . . . . . . . . . . .   7

     (a)    Restrictions Applicable to Company Registration. . . . . . . . .   7
     (b)    Restrictions Applicable to Demand Registration . . . . . . . . .   7

SECTION 6.  Registration Procedures. . . . . . . . . . . . . . . . . . . . .   9

SECTION 7.  Registration Expenses. . . . . . . . . . . . . . . . . . . . . .  14

SECTION 8.  Indemnification. . . . . . . . . . . . . . . . . . . . . . . . .  15

     (a)    Indemnification by Company . . . . . . . . . . . . . . . . . . .  15
     (b)    Indemnification by Holder of Registrable Securities. . . . . . .  16
     (c)    Contribution . . . . . . . . . . . . . . . . . . . . . . . . . .  17

- --------------------
*    This Table of Contents does not constitute a part of this Agreement or have
     any bearing upon the interpretation of any of its terms or provisions.


                                        i




SECTION 9.  Rule 144 . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18

SECTION 10.  Participation in Underwritten Registrations . . . . . . . . . .  18

SECTION 11.  Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . .  18

     (a)    Remedies . . . . . . . . . . . . . . . . . . . . . . . . . . . .  18
     (b)    No Inconsistent Agreements . . . . . . . . . . . . . . . . . . .  18
     (c)    Amendments and Waivers . . . . . . . . . . . . . . . . . . . . .  19
     (d)    Notices. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  20
     (e)    Successors and Assigns . . . . . . . . . . . . . . . . . . . . .  19
     (f)    Counterparts . . . . . . . . . . . . . . . . . . . . . . . . . .  20
     (g)    Headings . . . . . . . . . . . . . . . . . . . . . . . . . . . .  20
     (h)    Governing Law. . . . . . . . . . . . . . . . . . . . . . . . . .  20
     (i)    Severability . . . . . . . . . . . . . . . . . . . . . . . . . .  20
     (j)    Entire Agreement . . . . . . . . . . . . . . . . . . . . . . . .  20
     (k)    Limitations on Subsequent Registrations. . . . . . . . . . . . .  20


                                       ii




            THIS REGISTRATION RIGHTS AGREEMENT (the "AGREEMENT") is dated as of
April 15, 1996 and entered into by and between REGENERON PHARMACEUTICALS, INC.,
a New York corporation (the "COMPANY") and AMGEN INC., a Delaware corporation
(the "PURCHASER").

            This Agreement is made in connection with the execution and delivery
of the Stock and Warrant Purchase Agreement, dated as of the date hereof,
between the Company and the Purchaser (the "PURCHASE AGREEMENT").  In order to
induce the Purchaser to enter into the Purchase Agreement, the Company has
agreed to provide the registration rights set forth in this Agreement.

            The parties hereby agree as follows:

            SECTION 1.  DEFINITIONS.

            As used in this Agreement, the following capitalized terms shall
have the following meanings:

            AGENT:  Any Person authorized to act and who acts on behalf of the
Purchaser with respect to the transactions contemplated by this Agreement.

            COMMON STOCK:  The common stock, $.001 par value, of the Company.

            EXCHANGE ACT:  The Securities Exchange Act of 1934, as amended from
time to time.

            NASD:  National Association of Securities Dealers, Inc.

            PERSON:  An individual, partnership, corporation, limited liability
company, trust or unincorporated organization, or other business entity, or a
government or agency or political subdivision thereof.

            PROSPECTUS:  The prospectus included in any Registration Statement,
as amended or supplemented by any prospectus supplement with respect to the
terms of the offering of any portion of the Registrable Securities covered by
the Registration Statement and by all other amendments and supplements to the
prospectus, including post-effective amendments and all material incorporated by
reference in such prospectus.

            REGISTRABLE SECURITIES:  (i) the Common Stock acquired by the
Purchaser pursuant to the terms of the Purchase Agreement, and (ii) the Warrant
Shares.  Registrable Securities shall also include any securities which may be
issued or distributed with respect to, or in exchange for, such Registrable
Securities pursuant to a stock dividend, stock split or other


                                        1




distribution, merger, consolidation, recapitalization or reclassification or
similar transaction; PROVIDED, HOWEVER, that any such Registrable Securities
shall cease to be Registrable Securities to the extent (i) a Registration
Statement with respect to the sale of such Registrable Securities has been
declared effective under the Securities Act and such Registrable Securities have
been disposed of in accordance with the plan of distribution set forth in such
Registration Statement, (ii) such Registrable Securities are distributed
pursuant to Rule 144 (or any similar provision then in force) under the
Securities Act, or (iii) such Registrable Securities shall have been otherwise
transferred, new certificates for them not bearing a legend restricting transfer
under the Securities Act shall have been delivered by the Company and they may
be publicly resold without subsequent registration under the Securities Act or
in compliance with Rule 144 thereunder; PROVIDED, FURTHER, HOWEVER, that any
securities that have ceased to be Registrable Securities cannot thereafter
become Registrable Securities.

            REGISTRATION:  A registration of the Company's securities for sale
to the public under a Registration Statement.

            REGISTRATION EXPENSES:  See SECTION 7 hereof.

            REGISTRATION STATEMENT:  Any registration statement of the Company
filed with the Securities and Exchange Commission under the rules and
regulations promulgated under the Securities Act, including the Prospectus,
amendments and supplements to such Registration Statement, including post-
effective amendments, and all exhibits and all material incorporated by
reference in such Registration Statement.

            SECURITIES ACT:  The Securities Act of 1933, as amended from time to
time.

            SEC:  The Securities and Exchange Commission.

            UNDERWRITTEN REGISTRATION or UNDERWRITTEN OFFERING:  A Registration
in which securities of the Company are sold to an underwriter for reoffering to
the public.

            WARRANTS:  The Warrants, each to purchase shares of Common Stock,
issued and sold pursuant to the Purchase Agreement and the Warrant Agreement
dated as of the date hereof,  by and between the Company and the Purchaser (the
"WARRANT AGREEMENT").

            WARRANT SHARES:  Any shares of Common Stock issued or issuable upon
exercise of any of the Warrants.

            SECTION 2.  SECURITIES SUBJECT TO THIS AGREEMENT.

            (a)   REGISTRABLE SECURITIES.  The securities entitled to the
benefits of this Agreement are the Registrable Securities.

            (b)   HOLDERS OF REGISTRABLE SECURITIES.  A Person is deemed to be a
holder of Registrable Securities whenever such Person owns Registrable
Securities or has the right to acquire such Registrable Securities, whether or
not such ownership or right was acquired


                                        2




pursuant to the Purchase Agreement, or the Warrant Agreement, and whether or not
such acquisition has actually been effected and disregarding any legal
restrictions upon the exercise of such right.

            SECTION 3.  DEMAND REGISTRATIONS.

            (a)   DEMAND BY HOLDERS.  The holders of a majority of Registrable
Securities, at any time from and after the date hereof, may make a total of two
written requests to the Company for Registration of Registrable Securities under
and in accordance with the provisions of the Securities Act of all or part of
the Registrable Securities.  Any such Registration requested shall hereinafter
be referred to as a "DEMAND REGISTRATION."  Each request for a Demand
Registration shall specify the kind and aggregate amount of Registrable
Securities to be registered and the intended methods of disposition thereof.
Upon such request for a Demand Registration, the Company shall use its best
efforts to promptly effect the Registration of such Registrable Securities under
(i) the Securities Act, and (ii) subject to SECTION 6(h), the blue sky laws of
such jurisdictions as any holder of such Registrable Securities requesting such
Registration or any underwriter, if any, may reasonably request.  The Company
shall also use its best efforts to have all such Registrable Securities
registered with or approved by such other federal or state governmental agencies
or authorities as may be necessary in the opinion of counsel to the Company and
counsel to the holders of a majority of such Registrable Securities to
consummate the disposition of such Registrable Securities.

            Notwithstanding the foregoing, the Company shall not be obligated to
effect a Demand Registration if all (but not less than all) of the shares
requested to be registered could immediately be sold by such holders under Rule
144 under the Securities Act at a price substantially equivalent to the
prevailing market price.  The final determination of whether all of the shares
could immediately be sold under Rule 144 shall be made in good faith by counsel
for holders of the Registrable Securities after, among other things, considering
the possible affiliate status of any such holder.  The Company shall have the
burden of establishing that the shares could immediately be sold at a price
substantially equivalent to the prevailing market price.  In addition, the
Company shall not be required to effect a Demand Registration within six months
after the effective date of any Registration Statement filed at the request of
holders of Registrable Securities pursuant to the terms of this Agreement or the
Class D Convertible Preferred Stock Purchase Agreement dated as of August 31,
1990.  Any request for a Demand Registration not effected pursuant to the
provisions of this paragraph shall not count against the two requests specified
in the preceding paragraph.

            (b)   EFFECTIVE REGISTRATION.  Subject to the last paragraph of
SECTION 6, the Company shall be deemed to have effected a Demand Registration if
the Registration Statement relating to such Demand Registration is declared
effective by the SEC and remains effective for at least 90 days; PROVIDED,
HOWEVER, that no Demand Registration shall be deemed to have been effected if
(i) such registration, after it has become effective, is interfered with by any
stop order, injunction or other order or requirement of the SEC or other
governmental agency or court for any reason not attributable to the selling
holders of Registrable Securities, or (ii) the conditions to closing specified
in the purchase agreement or underwriting agreement entered into in connection
with such registration are not satisfied, other than by reason of a failure on
the


                                        3




part of the selling holders of Registrable Securities or any underwriter
referred to in SECTION 3(d).

            (c)   REGISTRATION STATEMENT FORM.  Registrations under this
SECTION 3 shall be on such appropriate registration form of the SEC as shall
permit the disposition of such Registrable Securities in accordance with the
intended method or methods of disposition specified in such holders' requests
for such Registration.  If, in connection with any Registration under this
SECTION 3 which is proposed by the Company to be on Form S-3 or any successor
form to such Form, the managing underwriter (if any) or holders of a majority of
the Registrable Securities requesting a Demand Registration shall advise the
Company in writing that in its opinion additional disclosure not required by
such form is of material importance to the success of the offering, then such
Registration shall include such additional disclosure.

            (d)   SELECTION OF UNDERWRITERS.  If at any time or from time to
time during the time period applicable to Demand Registrations any of the
holders of the Registrable Securities covered by a Registration Statement desire
to sell Registrable Securities in an Underwritten Offering, the investment
banker or investment bankers that will manage the offering will be selected as
follows:

               (1)       MANAGING UNDERWRITER.  A majority of the holders of
            Registrable Securities shall select three (or, if such holder(s)
            desires, more than three) nationally recognized investment banking
            firms as candidates for the offering, each of which is ready, 
            willing and able to act as the managing underwriter, and shall
            provide a list of such candidates to the Company.  Not later than
            five business days following the receipt of such list, the Company
            shall: (i) choose one of three candidates to act as the managing
            underwriter for the offering and (ii) notify the holders of a
            majority of Registrable Securities of such choice.

               (2)       CO-MANAGERS.  The investment banking firm(s), if any,
            that will serve as co-manager(s) of the offering will be selected by
            holders of a majority of Registrable Securities.

            (e)   REGISTRATION OF OTHER SECURITIES.  Whenever the Company shall
effect a Registration pursuant to this SECTION 3 in connection with an
Underwritten Offering by one or more holders of Registrable Securities, no
securities other than Registrable Securities shall be included among the
securities covered by such Registration if the managing underwriter of such
offering shall have advised each selling holder of Registrable Securities to be
covered by such Registration in writing (with a copy to the Company) that, in
its opinion, the number of securities requested to be included in such
Registration exceeds the number which can be sold in such offering within a
price range acceptable to the selling holders of a majority of the Registrable
Securities requested to be included in such Registration.  If no such notice or
letter is provided, the Company may include shares of Common Stock for its own
account or for the account of other shareholders of the Company having the right
to include such shares in a Registration Statement filed by the Company with the
SEC.


                                        4




            (f)   PRIORITY AMONG HOLDERS OF REGISTRABLE SECURITIES IN REQUESTED
REGISTRATION.  If the managing underwriter of an Underwritten Offering pursuant
to this SECTION 3 advises each of the holders of Registrable Securities in
writing (with a copy to the Company) that less than all of the Registrable
Securities proposed to be included in such offering should be included (using
the same standard described in subsection (e) hereof), then the amount of
Registrable Securities to be offered for the accounts of holders of Registrable
Securities shall be reduced pro rata, based on the number of Registrable
Securities owned by such holders.

            (g)   DELAY OF REQUESTED REGISTRATION.  Notwithstanding anything to
the contrary contained in this SECTION 3, if following a request for a Demand
Registration the Company provides prompt written notification to all holders of
Registrable Securities specifying the nature of any Delay Event described below,
then the filing of the Registration Statement pursuant to the request for Demand
Registration may be delayed by the Company for a period not to exceed six months
from the date of its receipt of the written request for the Demand Registration
or such shorter period provided below; provided, however, that such right to
delay a request may be exercised by the Company not more than once in any two
year period.  A "Delay Event" shall be defined as any of the following: (1) the
Company will file within 60 days following its receipt of the written request
for Demand Registration, a Registration Statement for the public offering of
securities for the account of the Company; (2) if the Securities Act or the
rules or regulations thereunder, or the form on which the Registration Statement
for the Demand Registration is to be filed, requires the filing of financial
statements which are not yet available (in which case, the Company shall prepare
or cause such statements to be prepared in a reasonably timely and diligent
manner and promptly thereafter file the Registration Statement); (3) at the time
of the request for Demand Registration, the Company is engaged in a material
transaction or has an undisclosed material corporate development, and in either
case, which would be required to be disclosed under the federal securities laws
in the Registration Statement, but the Company's Board of Directors has made a
good faith determination that making such disclosure at such time would
materially adversely affect such transaction or development (in which case, the
Company shall disclose the matter as promptly as practicable and promptly
thereafter file the Registration Statement); or (4) at the time of the request
of the Demand Registration, the Company is engaged in any financing (except the
type described in clause (1) above) (in which case the Company shall file the
Registration Statement no later than 30 days following its receipt of the
written request for Demand Registration).

            SECTION 4.  PIGGYBACK REGISTRATIONS.

            (a)   PARTICIPATION.  Subject to SECTION 4(b) hereof, if at any 
time from and after the date hereof, the Company proposes to file a 
Registration Statement under the Securities Act with respect to any offering 
of any of its shares of Common Stock, whether or not by the Company for its 
own account (other than (i) a registration on Form S-4 (or otherwise in 
connection with non-cash offerings, exchange offers, mergers or 
recapitalizations) or S-8 or any successor form to such Forms, or (ii) any 
registration of securities as it relates to an offering and sale to directors 
or employees of, or non-employee service providers to, the Company under 
bona fide benefits plans adopted by the Board of Directors of the Company and 
approved by the holders of Common Stock when required by law), then, as 
promptly as practicable, the Company shall give written notice of such 
proposed filing to each holder of Registrable Securities and such notice 
shall offer the holders of Registrable Securities the opportunity to register 
such number of Registrable

                                        5




Securities as each such holder may request (a "PIGGYBACK REGISTRATION").
Subject to SECTION 4(b), the Company shall include in such Registration
Statement all Registrable Securities requested within 15 days after the receipt
of any such notice (which request shall specify the Registrable Securities
intended to be disposed of by such holder) to be included in the Registration
for such offering pursuant to a Piggyback Registration.  Notwithstanding the
foregoing, the Company shall not be obligated to include in a Piggyback
Registration the shares of Registrable Securities requested to be included by a
holder of Registrable Securities if: (i) all (but not less than all) of the
shares requested to be included by that holder could immediately be sold by that
holder under Rule 144 under the Securities Act at a price substantially
equivalent to the prevailing market price and (ii) the Company provides to that
holder a written waiver and consent allowing such holder to sell or otherwise
dispose of all of such shares requested to be included without limitation to the
restrictions imposed by Section 5(a) hereof.  The final determination of whether
all of the shares could immediately be sold under Rule 144 shall be made in good
faith by counsel for such holder after, among other things, considering the
possible affiliate status of such holder.  The Company shall have the burden of
establishing that the shares could immediately be sold at a price substantially
equivalent to the prevailing market price.  Each holder of Registrable
Securities shall be permitted to withdraw all or part of such holder's
Registrable Securities from a Piggyback Registration at any time prior to the
effective date thereof.

            (b)   UNDERWRITER'S CUTBACK.  The Company shall use its best efforts
to cause the managing underwriter or underwriters of a proposed Underwritten
Offering to permit the Registrable Securities requested to be included in the
Registration for such offering under SECTION 4(a) (the "PIGGYBACK SECURITIES"),
to be included on the same terms and conditions as any similar securities
included therein.  Notwithstanding the foregoing, if the managing underwriter of
any such proposed Underwritten Offering informs the Company and the holders of
such Piggyback Securities in writing that, in its opinion, the number of shares
of Common Stock (including the Piggyback Securities) requested to be included in
such Registration exceeds the number which can be sold in such offering within a
price range acceptable to the party who has requested the filing of the
Registration Statement (the Company or other holders of the Company's Common
Stock, as the case may be, hereafter referred to as the "Requesting Party"),
then the shares of Common Stock to be included in such Registration shall be the
number that can be sold within a price range acceptable to the Requesting Party,
selected (i) first, from the shares of Common Stock originally proposed by the
Requesting Party to be included in the Registration for such offering, (ii)
second, and only if all the shares of Common Stock referenced in clause (i) have
been included, from shares of Common Stock subject to piggyback registration
rights originally proposed to be included by all holders of shares of Common
Stock (other than the Requesting Party), selected pro rata based upon the total
ownership of such shares of Common Stock subject to piggyback registration
rights of such holders, and (iii) third, and only if all of the shares of Common
Stock referenced in clause (ii) have been included, from any other securities
eligible for inclusion in such Registration.

            (c)   NO EFFECT ON DEMAND REGISTRATIONS.  No Registration of
Registrable Securities effected pursuant to a request under this SECTION 4 shall
be deemed to have been effected pursuant to SECTION 3 hereof or shall relieve
the Company of its obligation to effect any Registration upon request under
SECTION 3 hereof.


                                        6




            SECTION 5.  HOLD-BACK AGREEMENTS.

     (a)    RESTRICTIONS APPLICABLE TO COMPANY REGISTRATION.

            (1)   RESTRICTIONS APPLICABLE TO HOLDERS OF REGISTRABLE 
SECURITIES. Each holder of Registrable Securities, if requested by the 
Company and, in the case of an Underwritten Offering, the managing 
underwriters, shall agree not to sell, transfer or otherwise dispose of any 
Registrable Securities or other equity securities (or any securities 
convertible, exchangeable or exercisable for such equity securities) of the 
Company beneficially owned by it (except, in either case, those that are 
included in a Piggyback Registration) for a specified period of time (the 
"HOLDBACK PERIOD") in the event that the Company notifies such holder that it 
desires to file a Registration Statement (the "COMPANY REGISTRATION STATEMENT")
to register the sale of shares of Common Stock (or any securities convertible, 
exchangeable or exercisable for such Common Stock) (other than a Registration 
referred to in clause (i) or (ii) of Section 4(a)).  The Holdback Period shall 
commence on the date the Company Registration Statement is declared effective 
by the SEC and shall terminate 120 days thereafter.  A written agreement (the 
"Lock Up") memorializing each such holder's agreement to the foregoing 
restrictions shall be executed in a form reasonably satisfactory to the 
Company and, if applicable, the managing underwriters.

            (2)   RESTRICTIONS APPLICABLE TO OFFICERS, DIRECTORS AND OTHER 
STOCKHOLDERS,  As a condition to each holder's delivery of the Lock Up 
pursuant to SECTION 5(a)(1), the Company shall use its best efforts to obtain 
from each of its: (i) officers, (ii) directors and (iii) shareholders 
beneficially owning at least as many shares of Common Stock as the aggregate 
number of shares beneficially owned by the holders of Registrable Securities, 
a written agreement substantially similar to the Lock Up pursuant to which 
each such Person shall agree not to sell, transfer or otherwise dispose of 
any equity securities (or any securities convertible, exchangeable or 
exercisable for such equity securities) of the Company beneficially owned by 
it under the same terms as the Lock Up (excluding shares that are included in 
a Piggyback Registration); provided however, that each of the officers and 
directors may sell, transfer or dispose of during the Holdback Period the 
amount of equity securities of the Company that each would be permitted to 
sell under Rule 144 during a 90 day period commencing on the effective date 
of the Company Registration Statement.

     (b)    RESTRICTIONS APPLICABLE TO DEMAND REGISTRATION.  The following
restrictions on the sale, transfer or other disposition of the Company's equity
securities (or any securities convertible, exchangeable or exercisable for such
equity securities) by the Company, its officers and directors, certain other
shareholders and holders of Registrable Securities shall apply in the event of a
Demand Registration:

            (1)   REGISTRATION RESTRICTIONS APPLICABLE TO THE COMPANY.  The 
Company, if requested by the holders of a majority of Registrable Securities 
and, in the case of an Underwritten Offering, the managing underwriters, 
shall agree not to effect any public sale or distribution of its equity 
securities (or any securities convertible, exchangeable, or exercisable

                                        7




for such equity securities) (except those that may be included in a Piggyback 
Registration) or any private offer, sale or distribution of its equity 
securities (or any securities convertible, exchangeable or exercisable for 
such equity securities) that may be integrated under the federal securities 
laws or the regulations thereunder with a Demand Registration, for the 
Demand Registration Holdback Period in the event of a Demand Registration.  
The "Demand Registration Holdback Period" shall be defined as the period 
commencing on the date that the Registration Statement for the Demand 
Registration is declared effective by the SEC and shall terminate 120 days 
thereafter.  A written agreement memorializing the Company's agreement to the 
foregoing restrictions shall be executed in a form reasonably satisfactory to 
the holders of a majority of Registrable Securities and, if applicable, the 
managing underwriters.

            (2)   RESTRICTIONS APPLICABLE TO OFFICERS AND DIRECTORS.  The 
Company, if requested by the holders of a majority of Registrable Securities 
and, in the case of an Underwritten Offering, the managing underwriters, 
shall cause Dr. Leonard Schleifer (so long as he remains the Chief Executive 
Officer of the Company), and shall use its best efforts to cause each of its 
other officers and directors, to agree not to sell, transfer or otherwise 
dispose of any equity securities (or any securities convertible, 
exchangeable, or exercisable for such equity securities) of the Company 
beneficially owned by each such Person (except those that may be included in 
a Piggyback Registration) during the Demand Registration Holdback Period in 
the event of a Demand Registration; provided, however, that all such officers 
and directors in the aggregate may sell, transfer or otherwise dispose of an 
aggregate of up to five percent of the total number of shares included in the 
Demand Registration.  A written agreement memorializing each such Person's 
agreement to the foregoing restrictions shall be executed in a form 
reasonably satisfactory to the holders of a majority of Registrable 
Securities and, if applicable, the managing underwriters.

            (3)   RESTRICTIONS APPLICABLE TO OTHER STOCKHOLDERS.  The 
Company, if requested by the holders of a majority of Registrable Securities 
and, in the case of an Underwritten Offering, the managing underwriters, 
shall cause each holder of its privately placed equity securities (or any 
securities convertible, exchangeable, or exercisable for such equity 
securities) issued by the Company at any time on or after the date of this 
Agreement to agree (for the benefit of the holders of Registrable Securities) 
not to effect any public sale or distribution of any such securities during 
the Demand Registration Holdback Period in the event of a Demand 
Registration.  In addition, the Company shall use its best efforts to cause 
each such other shareholder of the Company beneficially owning at least five 
percent of the Company's then outstanding equity securities (OR any 
securities convertible, exchangeable, or exercisable for such equity 
securities) to agree not to effect any public sale or distribution of equity 
securities (or any securities convertible, exchangeable, or exercisable for 
such equity securities) of the Company during the Demand Registration 
Holdback Period in the event of a Demand Registration.  A written agreement 
memorializing each such Person's agreement to the foregoing restrictions 
shall be executed in a form reasonably satisfactory to the holders of a 
majority of Registrable Securities and, if applicable, the managing 
underwriters.

            (4)   RESTRICTIONS APPLICABLE TO THE HOLDERS OF REGISTRABLE
SECURITIES.  The holders of the Registrable Securities shall not sell, transfer
or otherwise dispose of any equity securities (or any securities convertible,
exchangeable or exercisable for such equity securities) of the Company
beneficially owned by them during a Demand Registration Holdback Period in the
event of any Demand Registration, except for those securities included in the
Demand Registration.



                                        8




            SECTION 6.  REGISTRATION PROCEDURES.

            In connection with the Company's registration obligations pursuant
to SECTIONS 3 AND 4 hereof, the Company will use its best efforts to effect such
registration to permit the sale of such Registrable Securities in accordance
with the intended method or methods of disposition thereof, and pursuant thereto
the Company will as expeditiously as possible:

            (a)   before filing a Registration Statement or Prospectus or any
     amendments or supplements thereto, furnish to the holders of the
     Registrable Securities covered by such Registration Statement and the
     underwriters, if any, copies of all such documents proposed to be filed,
     which documents will be subject to the review of such holders and
     underwriters, and the Company will not file any Registration Statement or
     amendment thereto or any Prospectus or any supplement thereto to which the
     holders of a majority of the Registrable Securities covered by such
     Registration Statement or the underwriters, if any, shall reasonably
     object;

            (b)   prepare and file with the SEC a Registration Statement or
     Registration Statements relating to the applicable Demand Registration or
     Piggyback Registration including all exhibits and financial statements
     required by the SEC to be filed therewith, and use its best efforts to
     cause such Registration Statement to become effective under the Securities
     Act; and prepare and file with the SEC such amendments and post-effective
     amendments to such Registration Statement, and such supplements to the
     Prospectus, as may be requested by any underwriter of Registrable
     Securities or as may be required by the rules, regulations or instructions
     applicable to the registration form utilized by the Company or by the
     Securities Act or rules and regulations otherwise necessary to keep the
     Registration Statement effective for a period of not less than 90 days (or
     such shorter period which will terminate when all Registrable Securities
     covered by such Registration Statement have been sold or withdrawn); and
     cause the Prospectus as so supplemented to be filed pursuant to Rule 424
     under the Securities Act; and comply with the provisions of the Securities
     Act and the Exchange Act with respect to the disposition of all securities
     covered by such Registration Statement during the applicable period in
     accordance with the intended methods of disposition by the sellers thereof
     set forth in such Registration Statement or supplement to the Prospectus;

            (c)   notify the selling holders of Registrable Securities and the
     managing underwriters, if any, promptly, and (if requested by any such
     Person) confirm such advice in writing,

               (1)    when the Prospectus or any Prospectus supplement or post-
            effective amendment has been filed, and, with respect to the
            Registration Statement or any post-effective amendment, when the
            same has become effective,

               (2)    of any request by the SEC for amendments or supplements to
            the Registration Statement or the Prospectus or for additional
            information,


                                        9




               (3)    of the issuance by the Commission of any stop order
            suspending the effectiveness of the Registration Statement or the
            initiation of any proceedings for that purpose,

               (4)    if at any time the representations and warranties of the
            Company contemplated by PARAGRAPH (o) below cease to be true and
            correct,

               (5)    of the receipt by the Company of any notification with
            respect to the suspension of the qualification of the Registrable
            Securities for sale in any jurisdiction or the initiation or
            threatening of any proceeding for such purpose, and

               (6)    of the existence of any fact which results in the
            Registration Statement, the Prospectus or any document incorporated
            therein by reference containing an untrue statement of material fact
            or omitting to state a material fact required to be stated therein
            or necessary to make the statements therein not misleading;

            (d)   make every reasonable effort to obtain the withdrawal of any
     order suspending the effectiveness of the Registration Statement at the
     earliest possible moment;

            (e)   if requested by the managing underwriter or underwriters or a
     holder of Registrable Securities being sold in connection with an
     Underwritten Offering, immediately incorporate in a Prospectus supplement
     or post-effective amendment such information as the managing underwriters
     and the holders of a majority of the Registrable Securities being sold
     agree should be included therein relating to the plan of distribution with
     respect to such Registrable Securities, including, without limitation,
     information with respect to the amount of Registrable Securities being sold
     to such underwriters, the purchase price being paid therefor by such
     underwriters and with respect to any other terms of the underwritten (or
     best efforts underwritten) offering of the Registrable Securities to be
     sold in such offering; and make all required filings of such Prospectus
     supplement or post-effective amendment as soon as notified of the matters
     to be incorporated in such Prospectus supplement or post-effective
     amendment;

            (f)   furnish to each selling holder of Registrable Securities and
     each managing underwriter, without charge, at least one signed copy of the
     Registration Statement and any post-effective amendment thereto, including
     financial statements and schedules, all documents incorporated therein by
     reference and all exhibits (including those incorporated by reference);

            (g)   deliver to each selling holder of Registrable Securities and
     the underwriters, if any, without charge, as many copies of the Prospectus
     (including each preliminary prospectus) and any amendment or supplement
     thereto as such Persons may reasonably request (it being understood that,
     unless one of clauses (2)-(6) of Section 6(c) is applicable, the Company
     consents to the use of the Prospectus or any amendment or


                                       10




     supplement thereto by each of the selling holders of Registrable Securities
     and the underwriters, if any, in connection with the offering and sale of
     the Registrable Securities covered by the Prospectus or any amendment or
     supplement thereto) and such other documents filed by the Company pursuant
     to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act as such selling
     holder may reasonably request in order to facilitate the disposition of the
     Registrable Securities by such holder and underwriters, if any;

            (h)   prior to any public offering of Registrable Securities,
     register or qualify or cooperate with the selling holders of Registrable
     Securities, the underwriters, if any, and their respective counsel in
     connection with the registration or qualification of such Registrable
     Securities for offer and sale under the securities or blue sky laws of such
     jurisdictions as any selling holder of Registrable Securities or any
     underwriter reasonably requests in writing and do any and all other acts or
     things reasonably necessary to enable the disposition in such jurisdictions
     of the Registrable Securities covered by the Registration Statement;
     PROVIDED THAT the Company will not be required to qualify generally to do
     business in any jurisdiction where it is not then so qualified or to take
     any action which would subject it to taxation or general service of process
     in any such jurisdiction where it is not then so subject;

            (i)   cooperate with the selling holders of Registrable Securities
     and the managing underwriters, if any, to facilitate the timely preparation
     and delivery of certificates representing Registrable Securities to be sold
     and not bearing any restrictive legends; and enable such Registrable
     Securities to be in such denominations and registered in such names as the
     managing underwriters may request at least two business days prior to any
     sale of Registrable Securities to the underwriters;

            (j)   use its best efforts to cause the Registrable Securities
     covered by the applicable Registration Statement to be registered with or
     approved by such other foreign governmental agencies or authorities, and
     the National Association of Securities Dealers, Inc., as may be necessary
     to enable the seller or sellers thereof or the underwriters, if any, to
     consummate the disposition of such Registrable Securities;

            (k)   if any fact contemplated by PARAGRAPH (c)(6) above shall
     exist, prepare a supplement or post-effective amendment to the Registration
     Statement or the related Prospectus or any document incorporated therein by
     reference or file any other required document so that, as thereafter
     delivered to the purchasers of the Registrable Securities, the Prospectus
     will not contain an untrue statement of a material fact or omit to state
     any material fact required to be stated therein or necessary to make the
     statements therein not misleading;

            (l)   cause all Registrable Securities covered by the Registration
     Statement to be quoted on the Nasdaq National Market or listed on each
     securities exchange on which similar securities issued by the Company are
     then listed if requested by the holders of a majority of such Registrable
     Securities or the managing underwriters, if any;


                                       11




            (m)   not later than the effective date of the applicable
     Registration Statement, provide a CUSIP number for all Registrable
     Securities and provide the applicable transfer agent with printed
     certificates for the Registrable Securities which are in a form eligible
     for deposit with Depositary Trust Company;

            (n)   enter into agreements (including underwriting agreements) and
     take all other appropriate actions in order to expedite or facilitate the
     disposition of such Registrable Securities and in such connection, whether
     or not an underwriting agreement is entered into and whether or not the
     registration is an Underwritten Registration:

                (1)   make such representations and warranties to the holders of
            such Registrable Securities and the underwriters, if any, in form,
            substance and scope as are customarily made by issuers to
            underwriters in primary Underwritten Offerings;

                (2)   obtain opinions of counsel to the Company (which counsel
            and opinions (in form, scope and substance) shall be reasonably
            satisfactory to the managing underwriters, if any, and the holders
            of a majority of the Registrable Securities being sold) addressed to
            each selling holder and the underwriters, if any, covering the
            matters customarily covered in opinions requested in primary
            Underwritten Offerings;

                (3)   obtain "cold comfort" letters and updates thereof from the
            Company's independent certified public accountants addressed to the
            underwriters, if any, such letters to be in customary form and
            covering matters of the type customarily covered in "cold comfort"
            letters by underwriters in connection with primary Underwritten
            Offerings;

                (4)   use its best efforts to obtain "cold comfort" letters and
            updates thereof from the Company's independent certified public
            accountants addressed to the selling holders of Registrable
            Securities, such letters to be in customary form and covering
            matters of the type customarily covered in "cold comfort" letters by
            underwriters in connection with primary Underwritten Offerings;

                (5)   if such an agreement is entered into, cause the same to
            set forth in full indemnification provisions and procedures
            substantially comparable to those set forth in SECTION 8 hereof with
            respect to all parties to be indemnified pursuant to said Section,
            including without limitation, all underwriters, sellers, brokers,
            dealers, managers and similar securities industry professionals
            participating in the distribution contemplated by such agreement,
            their officers and directors and each Person who controls such
            Persons (within the meaning of Section 15 of the Securities Act or
            Section 20 of the Exchange Act); and

                (6)   deliver such documents and certificates as may be
            reasonably requested in writing by the holders of a majority of the
            Registrable Securities being sold and the managing underwriters, if
            any, to evidence compliance with


                                       12




            PARAGRAPH (k) above and with any customary conditions contained in
            the underwriting agreement or other agreement entered into by the
            Company.

     The above shall be done as and to the extent required by the applicable
     agreement and by the then current practice;

            (o)   make available for inspection by any underwriter (including 
     any "qualified independent underwriter" that is required to be retained in
     accordance with the rules and regulations of the NASD) participating
     in any disposition pursuant to such Registration Statement, and any
     attorney or accountant retained by the underwriter, all financial and other
     records, pertinent corporate documents and properties of the Company, and
     cause the Company's officers, directors and employees to supply all
     information reasonably requested by any such underwriter, attorney or
     accountant in connection with the registration; PROVIDED that prior to any
     such Person being given access to such records, documents, properties or
     information such Person shall execute a reasonable and customary agreement
     to maintain the confidentiality of such records, documents, properties or
     information;

            (p)   otherwise use its best efforts to comply with all applicable
     rules and regulations of the SEC, and make generally available to its
     security holders, earnings statements satisfying the provisions of Section
     11(a) of the Securities Act, no later than 45 days after the end of any 12-
     month period (or 90 days, if such period is a fiscal year) (1) commencing
     at the end of any fiscal quarter in which Registrable Securities are sold
     to underwriters in an Underwritten Offering, or, if not sold to
     underwriters in such an offering, (2) beginning with the first month of the
     Company's first fiscal quarter commencing after the effective date of the
     Registration Statement, which statements shall cover said 12-month periods;

            (q)   cooperate and assist in any filings required to be made with
     the NASD and, subject to Section 6(o), in the performance of any due 
     diligence investigation by any underwriter (including any "qualified
     independent underwriter" that is required to be retained in accordance
     with the rules and regulations of the NASD); and

            (r)   promptly prior to the filing of any document which is to be
     incorporated by reference into the Registration Statement or the Prospectus
     (after initial filing of the Registration Statement) provide copies of such
     document to counsel to the selling holders of Registrable Securities and to
     the managing underwriters, if any, make the Company's representatives
     available for discussion of such document and make such changes in such
     document prior to the filing thereof as counsel for such selling holders or
     underwriters may reasonably request.

            The Company may require each seller of Registrable Securities as 
to which any registration is being effected to furnish to the Company such 
information regarding the distribution of such securities, and such other 
information about each such Seller as is required by the form of Registration 
Statement being used for such registration, as the Company may from time to 
time reasonably request in writing.

            Each holder of Registrable Securities agrees by acquisition of such
Registrable Securities that, upon receipt of any notice from the Company of the
happening of any event of the kind described in SECTION 6(c)(6) hereof, such
holder will forthwith discontinue disposition of


                                       13




Registrable Securities until such holder's receipt of the copies of the
supplemented or amended Prospectus contemplated by SECTION 6(k) hereof, or until
it is advised in writing by the Company that the use of the Prospectus may be
resumed, and has received copies of any additional or supplemental filings which
are incorporated by reference in the Prospectus, and, if so directed by the
Company, such holder will deliver to the Company (at the Company's expense) all
copies, other than permanent file copies then in such holder's possession, of
the Prospectus covering such Registrable Securities current at the time of
receipt of such notice.  In the event the Company shall give any such notice,
the time periods during which such Registration Statement shall be maintained
effective shall be extended by the number of days during the period from and
including the date of the giving of such notice to and including the date when
each seller of Registrable Securities covered by such Registration Statement
either receives the copies of the supplemented or amended prospectus
contemplated by SECTION 6(k) hereof or is advised in writing by the Company that
the use of the Prospectus may be resumed.

            SECTION 7.  REGISTRATION EXPENSES.

            (a)   All expenses incident to the Company's performance of or
compliance with this Agreement will be paid by the Company, regardless of
whether the Registration Statement becomes effective, including without
limitation:

            (1)   all registration and filing fees (including with respect to
     filings required to be made with the SEC);

            (2)   fees and expenses of compliance with securities or blue sky
     laws (including fees and disbursements of counsel for the underwriters or
     selling holders in connection with blue sky qualifications of the
     Registrable Securities and determination of their eligibility for
     investment under the laws of such jurisdictions as the managing
     underwriters or holders of a majority of the Registrable Securities being
     sold may designate);

            (3)   printing (including expenses of printing certificates for the
     Registrable Securities in a form eligible for deposit with the Depositary
     Trust Company and of printing prospectuses), messenger, telephone and
     delivery expenses;

            (4)   fees and disbursements of counsel for the (i) Company and (ii)
     the sellers of the Registrable Securities (subject to the provisions of
     SECTION 7(b) hereof);

            (5)   fees and disbursements of all independent certified public
     accountants of the Company (including the expenses of any "cold comfort"
     letters required by or incident to such performance);

            (6)   fees and expenses of other Persons retained by the Company;
     and

            (7)   all registration, filing and other fees and expenses
     associated with any NASD filing required to be made in connection with 
     the Registration Statement, including, if applicable, the fees and 
     expenses of any "qualified independent underwriter" (and its counsel) 
     that is required to


                                       14




     be retained in accordance with the rules and regulations of the NASD (all
     such expenses being herein called "REGISTRATION EXPENSES").

            The Company will, in any event, pay its internal expenses
(including, without limitation, all salaries and expenses of its officers and
employees performing legal or accounting duties), the expense of any annual
audit, the fees and expenses incurred in connection with the listing of the
securities to be registered on each securities exchange on which similar
securities issued by the Company are then listed, rating agency fees and the
fees and expenses of any Person, including special experts, retained by the
Company.

            (b)   In connection with each Registration Statement required
hereunder, the Company will reimburse the holders of Registrable Securities
being registered pursuant to such Registration Statement for the reasonable fees
and disbursements of not more than one counsel chosen by the holders of a
majority of such Registrable Securities.

            (c)   Each seller of the Registrable Securities shall pay all
discounts, commissions, fees and expenses of the underwriters, selling brokers,
dealer managers and similar industry professionals relating to the distribution
of its Registrable Securities.

            SECTION 8.  INDEMNIFICATION.

            (a)   INDEMNIFICATION BY COMPANY.  The Company agrees to indemnify
and hold harmless each holder of Registrable Securities, its officers,
directors, employees and Agents and each Person who controls such holder within
the meaning of either Section 15 of the Securities Act or Section 20 of the
Exchange Act (each such person being sometimes hereinafter referred to as an
"INDEMNIFIED HOLDER") from and against all losses, claims, damages, liabilities
and expenses (including reasonable costs of investigation and legal expenses)
arising out of or based upon any untrue statement or alleged untrue statement of
a material fact contained in any Registration Statement or Prospectus or in any
amendment or supplement thereto or in any preliminary prospectus, or arising out
of or based upon any omission or alleged omission to state therein a material
fact required to be stated therein or necessary to make the statements therein
not misleading, except insofar as such losses, claims, damages, liabilities or
expenses arise out of or are based upon any such untrue statement or omission or
allegation thereof based upon information furnished in writing to the Company by
such holder expressly for use therein; PROVIDED, HOWEVER, that the Company shall
not be liable in any such case to the extent that any such loss, claim, damage,
liability or expense arises out of or is based upon an untrue statement or
alleged untrue statement or omission or alleged omission in any Prospectus or
preliminary prospectus, if such untrue statement or alleged untrue statement,
omission or alleged omission is completely corrected in an amendment or
supplement to the Prospectus or preliminary prospectus and if, having previously
been furnished by or on behalf of the Company with copies of the Prospectus or
preliminary prospectus as so amended or supplemented, such holder thereafter
fails to deliver such Prospectus or preliminary prospectus as so amended or
supplemented, prior to or concurrently with the sale of a Registrable Security
to the person asserting such loss, claim, damage, liability or expense who
purchased such Registrable Security which is the subject thereof from such
holder.  This indemnity will be in addition to any liability which the Company
may otherwise have.


                                       15




            If any action or proceeding (including any governmental
investigation or inquiry) shall be brought or asserted against an Indemnified
Holder in respect of which indemnity may be sought from the Company, such
Indemnified Holder shall promptly notify the Company in writing, and the Company
shall assume the defense thereof, including the employment of counsel
satisfactory to such Indemnified Holder and the payment of all expenses.  Such
Indemnified Holder shall have the right to employ separate counsel in any such
action and to participate in the defense thereof, but the fees and expenses of
such counsel shall be at the expense of such Indemnified Holder unless (a) the
Company has agreed to pay such fees and expenses or (b) the Company shall have
failed to assume the defense of such action or proceeding and has failed to
employ counsel satisfactory to such Indemnified Holder in any such action or
proceeding or (c) the named parties to any such action or proceeding (including
any impleaded parties) include both such Indemnified Holder and the Company, and
such Indemnified Holder shall have been advised by counsel that there may be one
or more legal defenses available to such Indemnified Holder which are different
from or additional to those available to the Company (in which case, if such
Indemnified Holder notifies the Company in writing that it elects to employ
separate counsel at the expense of the Company, the Company shall not have the
right to assume the defense of such action or proceeding on behalf of such
Indemnified Holder, it being understood, however, that the Company shall not, in
connection with any one such action or proceeding or separate but substantially
similar or related actions or proceedings in the same jurisdiction arising out
of the same general allegations or circumstances, be liable for the reasonable
fees and expenses of more than one separate firm of attorneys at any time for
such Indemnified Holder and any other Indemnified Holders, which firm shall be
designated in writing by such Indemnified Holders).  The Company shall not be
liable for any settlement of any such action or proceeding effected without its
written consent, but if settled with its written consent, or if there be a final
judgment for the plaintiff in any such action or proceeding, the Company agrees
to indemnify and hold harmless such Indemnified Holders from and against any
loss or liability by reason of such settlement or judgment.

            (b)   INDEMNIFICATION BY HOLDER OF REGISTRABLE SECURITIES.  Each
holder of Registrable Securities agrees to indemnify and hold harmless the
Company, its directors and officers and each Person, if any, who controls the
Company within the meaning of either Section 15 of the Securities Act or Section
20 of the Exchange Act to the same extent as the foregoing indemnity from the
Company to such holder, but only with respect to (i) information relating to
such holder furnished in writing by such holder expressly for use in any
Registration Statement or Prospectus, or any amendment or supplement thereto, or
any preliminary prospectus and (ii) any loss, claim, damage, liability or
expense described in the proviso to the first sentence of SECTION 8(a).  In case
any action or proceeding shall be brought against the Company or its directors
or officers or any such controlling person, in respect of which indemnity may be
sought against a holder of Registrable Securities, such holder shall have the
rights and duties given the Company and the Company or its directors or officers
or such controlling person shall have the rights and duties given to each holder
by the preceding paragraph.  In no event shall the liability of any selling
holder of Registrable Securities hereunder be greater in amount than the dollar
amount of the proceeds received by such holder upon the sale of the Registrable
Securities giving rise to such indemnification obligation.


                                       16








            The Company shall be entitled to receive indemnities from
underwriters, selling brokers, dealer managers and similar securities industry
professionals participating in the distribution, to the same extent as provided
above with respect to information so furnished in writing by such Persons
specifically for inclusion in any Prospectus or Registration Statement or any
amendment or supplement thereto, or any preliminary prospectus.

            (c)   CONTRIBUTION.  If the indemnification provided for in this
SECTION 8 is unavailable to an indemnified party under SECTION 8(a) or SECTION
8(b) hereof (other than by reason of exceptions provided in those Sections) in
respect of any losses, claims, damages, liabilities or expenses referred to
therein, then each applicable indemnifying party, in lieu of indemnifying such
indemnified party, shall contribute to the amount paid or payable by such
indemnified party as a result of such losses, claims, damages, liabilities or
expenses in such proportion as is appropriate to reflect the relative fault of
the Company on the one hand and of the Indemnified Holder on the other in
connection with the statements or omissions which resulted in such losses,
claims, damages, liabilities or expenses, as well as any other relevant
equitable considerations.  The relative fault of the Company on the one hand and
of the Indemnified Holder on the other shall be determined by reference to,
among other things, whether the untrue or alleged untrue statement of a material
fact or the omission or alleged omission to state a material fact relates to
information supplied by the Company or by the Indemnified Holder and the
parties' relative intent, knowledge, access to information and opportunity to
correct or prevent such statement or omission.  The amount paid or payable by a
party as a result of the losses, claims, damages, liabilities and expenses
referred to in SECTION 8(a) or SECTION 8(b) shall be deemed to include, subject
to the limitations set forth in the second paragraph of SECTION 8(a), any legal
or other fees or expenses reasonably incurred by such party in connection with
investigating or defending any action or claim.

            The Company and each holder of Registrable Securities agree that 
it would not be just and equitable if contribution pursuant to this SECTION 
8(c) were determined by pro rata allocation or by any other method of 
allocation which does not take account of the equitable considerations 
referred to in the immediately preceding paragraph. Notwithstanding the 
provisions of this SECTION 8(c), an Indemnified Holder shall not be required 
to contribute any amount in excess of the amount by which the total price at 
which the Registrable Securities sold by such Indemnified Holder or its 
affiliated Indemnified Holders and distributed to the public were offered to 
the public exceeds the amount of any damages which such Indemnified Holder, 
or its affiliated Indemnified Holder, has otherwise been required to pay by 
reason of such untrue or alleged untrue statement or omission or alleged 
omission.  No person guilty of fraudulent misrepresentation (within the 
meaning of Section 11(f) of the Act) shall be entitled to contribution from 
any person who was not guilty of such fraudulent misrepresentation.

            SECTION 9.  RULE 144.

            The Company covenants that it will file the reports required to be
filed by it under the Securities Act and the Exchange Act and the rules and
regulations adopted by the SEC thereunder, and, so long as the Company is
subject to the reporting requirements of the Exchange Act and the rules and
regulations thereunder, it will take such further action as any holder of
Registrable Securities may reasonably request, all to the extent required from
time to


                                       17




time to enable such holder to sell Registrable Securities without registration
under the Securities Act within the limitation of the exemptions provided by (a)
Rule 144 under the Securities Act, as such Rule may be amended from time to
time, or (b) any similar rule or regulation hereafter adopted by the SEC.  Upon
the request of any holder of Registrable Securities, the Company will deliver to
such holder a written statement as to whether it has complied with such
information and requirements.

            SECTION 10.  PARTICIPATION IN UNDERWRITTEN REGISTRATIONS.

            No Person may participate in any Underwritten Registration hereunder
unless such Person (a) agrees to sell such Person's securities on the basis
provided in any underwriting arrangements approved by the Persons entitled
hereunder to approve such arrangements and (b) completes and executes all
questionnaires, powers of attorney, indemnities, underwriting agreements and
other documents required under the terms of such underwriting arrangements.

            SECTION 11.  MISCELLANEOUS.

            (a)   REMEDIES.  Each of the parties hereto, in addition to being 
entitled to exercise all rights provided herein, in the Purchase Agreement 
and granted by law, including recovery of damages, will be entitled to 
specific performance of its rights under this Agreement.  Each of the parties 
hereto agrees that monetary damages would not be adequate compensation for 
any loss incurred by reason of a breach by it of the provisions of this 
Agreement and hereby agrees to waive the defense in any action for specific 
performance that a remedy at law would be adequate.

            (b)   NO INCONSISTENT AGREEMENTS.  The Company will not on or after
the date of this Agreement enter into any agreement with respect to its
securities which is inconsistent with the rights granted to the holders of
Registrable Securities in this Agreement or otherwise conflicts with the
provisions hereof.  The Company represents and warrants that the rights granted
to the holders of Registrable Securities hereunder do not in any way conflict
with and are not inconsistent with the rights granted to the holders of the
Company's securities under any agreement in effect on the date hereof.

            (c)   AMENDMENTS AND WAIVERS.  The provisions of this Agreement,
including the provisions of this sentence, may not be amended, modified or
supplemented, and waivers or consents to departures from the provisions hereof
may not be given unless the Company has obtained the written consent of holders
of at least a majority of the outstanding Registrable Securities.
Notwithstanding the foregoing, a waiver or consent to departure from the
provisions hereof that relates exclusively to the rights of holders of
Registrable Securities whose securities are being sold pursuant to a
Registration Statement and that does not directly or indirectly affect the
rights of other holders of Registrable Securities may be given by the holders of
a majority of the Registrable Securities being sold.

            (d)   NOTICES.  Unless otherwise provided herein, any notice,
request, instruction or other document to be given hereunder by any party to the
others shall be in writing and delivered in person or by courier, telegraphed,
telexed or by facsimile transmission (with receipt


                                       18




confirmed), or mailed by certified mail, postage prepaid, return receipt
requested (such mailed notice to be effective on the date of such receipt is
acknowledged), as follows:

     (i) if to a holder of Registrable Securities, at the most current address
     given by such holder to the Company in accordance with the provisions of
     this Section 11(d), which address initially is, with respect to the
     Purchaser:

                  Amgen Inc.
                  Amgen Center
                  1840 DeHavilland Drive
                  Thousand Oaks, California 91320-1789
                  Attn: Corporate Secretary
                  Telecopy No.: (805) 499-9315

     With a copy to:

                  Latham & Watkins
                  633 West Fifth Street
                  Los Angeles, California 90071
                  Attn: Michael W. Sturrock, Esq.
                  Telecopy No.: (213) 891-8763

     (ii) if to the Company, initially to:

                  Regeneron Pharmaceuticals, Inc.
                  777 Old Saw Mill River Road
                  Tarrytown, New York 10591-6707
                  Attn: Corporate Secretary
                  Telecopy No.: (914) 345-7721

     With a copy to:

                  Skadden, Arps, Slate, Meagher & Flom
                  919 Third Avenue
                  New York, New York 10022
                  Attn: Morris Kramer, Esq. and Matthew J. Mallow, Esq.
                  Telecopy No.: (212) 735-2000

or to such other place and with such other copies as either party may designate
as to itself by written notice to the others.

            (e)   SUCCESSORS AND ASSIGNS.  This Agreement shall inure to the
benefit of and be binding upon the successors and assigns of each of the
parties, including without limitation and without the need for an express
assignment, subsequent holders of Registrable Securities; provided, however,
that this Agreement shall not inure to the benefit of or be binding upon a
successor or assign of a holder of Registrable Securities unless such successor


                                       19




or assign (i) acquired Registrable Securities from a holder of Registrable 
securities who was bound by the terms of this Agreement and (ii) agrees
to be bound by the terms of this Agreement.

            (f)   COUNTERPARTS.  This Agreement may be executed in any number of
counterparts and by the parties hereto in separate counterparts, each of which
when so executed shall be deemed to be an original and all of which taken
together shall constitute one and the same agreement.

            (g)   HEADINGS.  The headings in this Agreement are for convenience
of reference only and shall not limit or otherwise affect the meaning hereof.

            (h)   GOVERNING LAW.  This Agreement shall be governed by and
construed in accordance with the laws of the State of New York.

            (i)   SEVERABILITY.  In the event that any one or more of the
provisions contained herein, or the application thereof in any circumstance, is
held invalid, illegal or unenforceable, the validity, legality and
enforceability of any such provision in every other respect and of the remaining
provisions contained herein shall not be affected or impaired thereby.

            (j)   ENTIRE AGREEMENT.  This Agreement is intended by the parties
as a final expression of their agreement and intended to be a complete and
exclusive statement of the agreement and understanding of the parties hereto in
respect of the subject matter contained herein.  There are no restrictions,
promises, warranties or undertakings, other than those set forth or referred to
herein with respect to the registration rights granted by the Company with
respect to the securities sold pursuant to the Purchase Agreement. This
Agreement supersedes all prior agreements and understandings between the parties
with respect to such subject matter.

            (k)   LIMITATIONS ON SUBSEQUENT REGISTRATIONS.  After the date
hereof, the Company shall not, without the prior written consent of the holders
of at least 50% of the Registrable Securities, enter into any agreement (other
than this Agreement) with any holder or prospective holder of any securities for
the Company which would allow such holder or prospective holder to make a demand
registration, after the holders of Registrable Securities have made a Demand
Registration, which could result in such Registration Statement being declared
effective prior to such Demand Registration.


                           [Signature Page To Follow]


                                       20




            IN WITNESS WHEREOF, the parties have executed this Agreement as of
the date first written above.

                                   REGENERON  PHARMACEUTICALS, INC.



                                   By:
                                       ------------------------------------
                                       Name:
                                       Title:




                                   AMGEN INC.



                                   By:
                                       ------------------------------------
                                       Name:
                                       Title:



                                       S-1