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                                                                     Exhibit 4.2

                          AMENDMENT TO RIGHTS AGREEMENT

1.       General Background. In accordance with Section 27 of the Rights
         Agreement between Fleet National Bank, N.A. (f/k/a BankBoston, N.A.)"
         (the "Rights Agent") and Applera Corporation ("Applera") dated April
         28, 1999 (the "Agreement"), the Rights Agent and Applera Corporation,
         desire to amend the Agreement to appoint EquiServe Trust Company, N.A.

2.       Effectiveness. This Amendment shall be effective as of April 17, 2002
         (the "Amendment") and all defined terms and definitions in the
         Agreement shall be the same in the Amendment except as specifically
         revised by the Amendment.

3.       Revision. The section in the Agreement entitled "Change of Rights
         Agent" is hereby deleted in its entirety and replaced with the
         following:

         Change of Rights Agent.  The Rights Agent or any successor Rights Agent
         may resign and be discharged from its duties under this Agreement upon
         30 days' notice in writing mailed to the Company and to each transfer
         agent of the Common Stock or Preferred Stock by registered or certified
         mail and, following the Distribution Date, to the holders of the Right
         Certificates by first-class mail. The Company may remove the Rights
         Agent or any successor Rights Agent upon 30 days' notice in writing,
         mailed to the Rights Agent or successor Rights Agent, as the case may
         be, and to each transfer agent of the Common Stock or Preferred Stock
         by registered or certified mail, and, following the Distribution Date,
         to the holders of the Right Certificates by first-class mail. If the
         Rights Agent shall resign or be removed or shall otherwise become
         incapable of acting, the Company shall appoint a successor to the
         Rights Agent. If the Company shall fail to make such appointment within
         a period of 30 days after giving notice of such removal or after it has
         been notified in writing of such resignation or incapacity by the
         resigning or incapacitated Rights Agent or by the holder of a Right
         Certificate (who shall, with such notice, submit such holder's Right
         Certificate for inspection by the Company), then the registered holder
         of any Right Certificate may apply to any court of competent
         jurisdiction for the appointment of a new Rights Agent. Any successor
         Rights Agent, whether appointed by the Company or by such a court,
         shall be a corporation or trust company organized and doing business
         under the laws of the United States or any state thereof, in good
         standing, which is authorized under such laws to exercise corporate
         trust or stock transfer powers and is subject to supervision or
         examination by federal or state authority and which has individually or
         combined with an affiliate at the time of its appointment as Rights
         Agent a combined capital and surplus of at least $100 million dollars.
         After appointment, the successor Rights Agent shall be vested with the
         same powers, rights, duties and responsibilities as if it had been
         originally named as Rights Agent without further act or deed; but the
         predecessor Rights Agent shall deliver and transfer to the successor
         Rights Agent any property at the time held by it hereunder, and execute
         and deliver any further assurance, conveyance, act or deed necessary
         for the purpose. Not later than the effective date of any such
         appointment the Company shall file notice thereof in writing with the
         predecessor Rights Agent and each transfer agent of the Common Stock or
         Preferred Stock, and mail a notice thereof in writing to the registered
         holders of the Right Certificates. Failure to give any notice provided
         for in this Section 21, however, or any defect therein, shall not
         affect the legality or validity of the resignation or removal of the
         Rights Agent or the appointment of the successor Rights Agent, as the
         case may be.

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4.       Except as amended hereby, the Agreement and all schedules or exhibits
         thereto shall remain in full force and effect.

IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed
in their names and on their behalf by and through their duly authorized
officers, as of this 17th day of April, 2002.

Applera Corporation                         Bank Boston, N.A.

       /s/ Thomas P. Livingston                    /s/ Tyler Haynes
------------------------------------        ------------------------------------
By:      Thomas P. Livingston               By:      Tyler Haynes
Title:   Secretary                          Title:   Managing Director



                                            EquiServe Trust Company, N.A.

                                                   /s/ Tyler Haynes
                                            -----------------------------------
                                            By:      Tyler Haynes
                                            Title:   Managing Director