Document:

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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.

<PAGE>

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<PAGE>

                                                                  EXHIBIT 10.13

                                FOURTH AMENDMENT
                             THE EXCESS BENEFIT PLAN
                                       OF
                          THE PERKIN-ELMER CORPORATION

WHEREAS, the PE Corporation ("Company") last restated The Excess Benefit Plan of
The Perkin-Elmer Corporation ("Plan") effective October 1, 1995; and

WHEREAS, the Board of Directors of the Company pursuant to Section 6.1 of the
Plan reserves the right to amend the Plan from time to time; and

WHEREAS, it has been determined that an amendment is required at this time.

NOW, THEREFORE, the Plan be amended as stipulated below:

1.       Effective October 1, 2001, Section 4.1(b) of the Plan is amended to
         replace the "Vanguard Life Strategy Moderate Growth Fund" with the
         "Fidelity Asset Manager Fund as held by The Employee 401(k) Savings
         Plan of the Applera Corporation."

2.       Effective October 1, 2001, Article 6 of the Plan is amended by the
         addition of a new section which shall be titled Section 6.2 and shall
         now read as follows:

         "The Committee shall be granted the authority to make administrative
         changes to the Plan document by amendment of the Plan authorized by
         resolution of the Committee. Administrative changes include, but are
         not limited to, conforming provisions for administrative procedures to
         actual practice or changes in practice; deleting or correcting language
         that fails to accurately reflect the intended provisions of the Plan;
         updates for different funds used to measure performance; changes to the
         name of the Plan and Company; and implementing policy decisions that
         assist or clarify the administration of the Plan."<PAGE>

                                                                  EXHIBIT 10.22

                                  PARACEL, INC.
                                STOCK OPTION PLAN

1. Purpose

         The purposes of the Paracel, Inc. Stock Option Plan are to assist
Paracel, Inc. in attracting, motivating and retaining key employees, consultants
and directors, and to provide incentives that will further its development and
success and will unify the interests of key employees, consultants, directors
and shareholders through increased stock ownership.

2. Definitions

         For purposes of this Plan:

         "Board" means the Board of Directors of the Company.

         "Code" means the Internal Revenue Code of 1986, as amended.

         "Committee" means the Stock Option Committee appointed pursuant to
Section 13 of this Plan.

         "Company" means Paracel, Inc., a California corporation.

         "Consultant" means any person who is a consultant to the Company or to
any Subsidiary Corporation, as defined in Rule 701 promulgated under the
Securities Act.

         "Director" means any person who is a member of the Board.

         "Employee" means any person who is an employee of the Company or of any
Subsidiary Corporation.

         "Exchange Act" means the Securities Exchange Act of 1934, as amended.

         "Incentive Stock Option" means and Option that is designated by the
Committee as an "incentive stock option" within the meaning of Code Section 422.

         "Nonstatutory Option" means an Option that is designated by the
Committee as such or that is not designated by the Committee as an Incentive
Stock Option.

         "Option" means an option granted under this Plan to purchase shares of
Stock. An "Option" may be either an Incentive Stock Option or a Nonstatutory
Option.

         "Parent Corporation" shall have the meaning set forth in Code Section
424(e).

                                       -1-

<PAGE>

         "Participant" means a person to whom an Option is granted under this
Plan.

         "Permanent Disability" means permanent and total disability within the
meaning of Code Section 22(e)(3), which reads, in pertinent part, as follows:

                  An individual is permanently and totally disabled if he is
                  unable to engage in any substantial gainful activity by reason
                  of any medically determinable physical or mental impairment
                  which can be expected to result in death or which has lasted
                  or can be expected to last for a continuous period of not less
                  than 12 months.

         "Plan" means this Paracel, Inc. Stock Option Plan.

         "Retirement" means normal retirement of an Employee under policies
established by his or her employer.

         "Securities Act" means the Securities Act of 1933, as amended.

         "Stock" means the Common Stock of the Company. Unless the context
expressly indicates otherwise, "shares" means shares of Stock.

         "Subsidiary Corporation" shall have the meaning set forth in Code
Section 424(f).

         "Ten Percent Shareholder" means an Employee who on the date of grant of
the Option owns (within the meaning of Code Section 424(d)) more than 10% of the
total combined voting power of all classes of stock of the Company, any
Subsidiary Corporation or any Parent Corporation.

3. Shares Subject to Plan

         Options may be granted under this Plan to acquire an aggregate of up to
750, 000 shares of Stock, subject to adjustment as provided in Section 7 of this
Plan. If Options terminate, expire or are cancelled without having been fully
exercised, the number of shares subject to such Options (but only to the extent
not exercised prior to termination, expiration or cancellation) may again be
subject to Options granted under this Plan.

4. Eligibility

         Any Key Employee, any Consultant and any Director shall be eligible to
become a Participant and to be granted an Option to purchase Stock. Additional
Options may be granted to a Participant while such Participant continues as an
Employee, Consultant or Director. The Committee may exclude otherwise eligible
persons.

                                      -2-
<PAGE>

5. Grant of Options

         The Committee shall, from time to time and in its absolute discretion,
determine which Employees are key Employees and which eligible persons shall
become Participants. Either Incentive Stock Options or Nonstatutory Options, as
determined by the Committee in its absolute discretion, may be granted to
Employees, and only Nonstatutory Options may be granted to Consultants and to
Directors who are not Employees. The Committee also shall determine the number
of shares of Stock to be subject to each Option and the price, terms and
conditions, consistent with this Plan, of each Option.

         Without limiting the generality of the preceding paragraph, the
Committee may, in its discretion and on such terms as it deems appropriate,
require as a condition to the grant of an Option to an Employee, Consultant or
Director, that the Employee, Consultant or Director surrender for cancellation
some or all of any unexercised Options which have been previously granted to the
Employee, Consultant or Director. An Option, the grant of which is conditioned
upon such surrender, may have an option price lower or higher than the option
price of the surrendered Option, may cover the same, or a lesser or greater,
number of shares as the surrendered Option, may contain such other terms as the
Committee deems appropriate and shall be exercisable in accordance with its
terms, without regard to the number of shares, price, option period or any other
term or condition of the surrendered Option.

         Notwithstanding any other provision of this Plan, the aggregate fair
market value (determined as of the dates of their respective grants) of shares
as to which Incentive Stock Options (within the meaning of Code Section 422(b))
granted or assumed by the Company, any Parent Corporation and any Subsidiary
Corporation first become exercisable by a Participant in any calendar year shall
not exceed $100,000. Should it be determined that an entire Option granted under
this Plan or any portion thereof exceeds such maximum for any reason other than
the failure of a good faith attempt to value the stock subject to the Option,
such Option or portion thereof shall be considered a Nonstatutory Option to the
extent, but only to the extent, of such excess.

6. Option Terms

         Each Option shall be evidenced by a written Stock Option Agreement in a
form approved by the Committee. Each Stock Option Agreement shall be executed by
the Company and by the Participant receiving the Option. Each Option shall be
subject to the following terms and conditions and to such other terms and
conditions as the Committee may deem appropriate:

         6.1 Type of Option; Number of Shares

                  Each Stock Option Agreement shall indicate whether the Option
is an Incentive Stock Option or a Nonstatutory Option and shall specify the
number of shares of Stock subject to the Option.

                                      -3-
<PAGE>

         6.2 Option Price

                  The price of the shares subject to each Option shall be
determined by the Committee and shall be set forth in the Stock Option
Agreement, provided that the price per share shall not be less than the fair
market value of such share on the day the Option is granted; and provided
further that, in the case of an Incentive Stock Option granted to a Ten Percent
Shareholder, the price per share shall not be less than 110% of the fair market
value of such share at the time such Option is granted.

         6.3 Period of Exercise

                  No Option shall be exercisable in whole or in part before one
year from the date of grant or after ten years from the date of grant.
Notwithstanding the foregoing, no Incentive Stock Option granted to a Ten
Percent Shareholder may be exercisable after five years from the date such
Option is granted. Subject to the forgoing limitations and Sections 6.5, 6.7 and
8 of this Plan, Options shall become exercisable at such times and in such
installments (which may be cumulative) as the Committee shall provide in each
Stock Option Agreement.

                  The Committee may in its absolute discretion, and on such
terms and conditions as it considers appropriate, accelerate the times at which
an Option may be exercised in whole or in part.

         6.4 Manner and Conditions of Exercise

                  To exercise an Option or any portion thereof, the Participant
or other person then entitled to exercise such Option or portion thereof shall
deliver to the Secretary of the Company a notice in writing signed by the
Participant or such other person stating that such Option or portion is
exercised, specifying the number of shares to be acquired upon exercise and
complying with all applicable rules established by the Committee, together with
the following:

                  (a) Full payment (in cash or bank cashiers' check) for the
         shares with respect to which such Option or portion is being exercised;
         or

                  (b) With the consent of the Committee, shares of Stock owned
         by the Participant, duly endorsed for transfer to the Company, with a
         fair market value on the date of exercise equal to the aggregate
         purchase price of the shares with respect to which such Option or
         portion is being exercised; or

                  (c) With the consent of the Committee, a full recourse
         promissory note in a form, bearing interest (at a rate at least equal
         to the minimum rate necessary to avoid imputed interest under the Code)
         and payable upon such terms as may be prescribed by the Committee; or

                  (d) Any combination of the consideration provided in the
         foregoing subsections (a), (b) and (c).

                                      -4-
<PAGE>

No such exercise shall be effective unless and until a proper notice and payment
have been delivered as provided above. No fractional shares shall be issued on
exercise of Options under this Plan.

                  In the event that an Option or portion thereof shall be
exercised pursuant to Section 6.5 of this Plan by any person or persons other
than the Participant, appropriate proof of the right of such person or persons
to exercise the Option or portion thereof shall be delivered to the Company.

                  The Committee may require, as a condition to the exercise of
an Option, such representations and covenants as it, in its absolute discretion,
deems necessary to effect compliance with the Securities Act, any state
securities laws or rules and regulations thereunder, including a representation
that the shares to be acquired upon exercise of an Option will be purchased for
the Participant's own account and not with a view to or for sale in connection
with any distribution of the Stock.

                  The Participant, as a condition to exercising an Option, shall
also make any arrangements determined by the Committee to be necessary or
appropriate to satisfy any federal and state withholding tax obligation
resulting from the exercise of an Option, from a disposition described in
Section 9 of this Plan or from the termination or partial termination of any
restriction applicable to any shares acquired on exercise of an Option,
including the retention of shares by the Company or the delivery of shares to
the Company equal in amount to all or a portion of the withholding tax
obligation pursuant to such arrangements as may be established by the Committee.
Any shares retained by or delivered to the Company under this Section shall be
valued at the date of exercise at their fair market value as determined by the
Committee.

                  To insure that such exercise and any resales are made in
compliance with the Securities Act and the Articles of Incorporation and Bylaws
of the Company, the Company may imprint an appropriate legend on certificates
representing shares acquired on the exercise of an Option and issue appropriate
stop-transfer orders to its transfer agents. Any stock certificate evidencing
shares of Stock issued pursuant to the exercise of an Option shall bear such
other legends as the Committee, in the exercise of its absolute discretion,
shall require.

         6.5 Cessation of Employment or Service as Consultant or Director

                  A Stock Option Agreement may provide, on such terms and
conditions as the Committee shall deem appropriate in its absolute discretion,
for acceleration of the times at which an Option may be exercised in the event
of a Participant's Retirement, death or Permanent Disability, and may provide
for expiration prior to the stated expiration date in the event of cessation of
employment or service as a Consultant or Director. In the absence of provision
in the Stock Option Agreement, Options shall be accelerated or expire as set
forth below in this Section 6.5.

                                      -5-
<PAGE>

                  If a Participant who is an Employee but is not a Director
ceases to be an Employee other than by reason of death or Permanent Disability,
the Participant shall be permitted to exercise his or her Option, to the extent
it was exerciseable at the date of cessation, until 30 days after such date, but
in no event after its stated expiration date.

                  If a Participant who is a Consultant or Director but not an
Employee ceases to be a Consultant or Director, other than by reason of death,
the Participant shall be permitted to exercise his or her Option, to the extent
it was exercisable at the date of cessation, until 30 days after such date, but
in no event after its stated expiration date.

                  If a Participant who is an Employee but not a Director ceases
to be an Employee because of Permanent Disability, the Participant shall be
permitted to exercise his or her Option, to the extent it was exercisable at the
date of cessation of employment, until 90 days after the date he or she ceases
to be an Employee, but in no event after its stated expiration date.

                  If a Participant dies while an Employee, a Director or a
Consultant or within 90 days after ceasing to be an Employee because of
Permanent Disability, his or her Option may be exercised by the Participant's
estate or any person who acquired the right to exercise the Option by Will or
the laws of decent and distribution, to the extent it was exercisable at the
date of death, until one year after such date, but in no event after its stated
expiration date.

                  If a Participant who is both an Employee and a Director ceases
to be an Employee but remains a Director, or ceases to be a Director but remains
an Employee, then subject to this Section 6.5 all of the Participant's
Nonstatutory Options shall remain in effect and, if the Participant ceases to be
an Employee, all of the Participant's Incentive Stock Options shall become
Nonstatutory Options 30 days after the date of cessation.

                  Transfers of employment between the Company and any Subsidiary
Corporation or between Subsidiary Corporations shall not be deemed cessation of
employment for purposes of any Option granted hereunder.

         6.6 Nontransferability

                  During the lifetime of a Participant, his or her Options shall
be exercisable only by the Participant and no Option shall be transferable other
than by Will or the laws of descent and distribution. No interest of any
Participant under this Plan or in any Option shall be subject to attachment,
execution, garnishment, sequestration, the laws of bankruptcy or any other legal
or equitable process.

                                      -6-
<PAGE>

         6.7 Stock Restriction Agreement

                  In its absolute discretion, and on such terms and conditions
as it deems appropriate, the Committee may require by the terms of any Option
that Stock received upon exercise of such Option is subject to the Participant's
execution and delivery of an agreement providing for (i) a right of first
refusal for the benefit of the Company, and (ii) repurchase by the Company on
the occurrence of certain events, including the death, disability, retirement or
termination of employment of the Participant. The execution and delivery of such
an agreement prior to the delivery of any shares issued upon exercise of an
Option containing such a requirement shall be a condition precedent to the right
of a Participant to acquire any shares upon exercise of the Option.

7. Adjustment Upon Changes in Capitalization

         In the event of any change in the Stock by reason of any stock
dividend, recapitalization, split-up, combination or exchange of shares, or by
reason of any similar change affecting the Stock (but not the issuance of
additional shares, securities convertible into shares or options or rights to
acquire shares of Stock or the Company's repurchase of shares), the number and
class of shares which thereafter may be acquired on exercise of Options under
Section 3 of this Plan and the number and class of shares subject to outstanding
Options and the exercise price of each such share shall be appropriately
adjusted consistent with such change in such manner as the Committee may deem
equitable to prevent substantial dilution or enlargement of the rights granted
to, or available for, Participants. Any such adjustment shall be final and
binding on each Participant.

8. Merger, Consolidation, Etc.

         In its absolute discretion, and on such terms and conditions as it
deems appropriate, the Committee may provide by the terms of any Option that
such Option cannot be exercised after the merger or consolidation of the Company
with or into another corporation, the acquisition by another corporation or
person of all or substantially all of the Company's assets or the liquidation or
dissolution of the Company; and if the Committee so provides, it may, in its
absolute discretion, and on such terms and conditions as it deems appropriate,
also provide, either by the terms of such Option or by a resolution adopted
prior to the occurrence of such merger, consolidation, acquisition, liquidation
or dissolution, that, for some period of time prior to such event, such Option
shall become exercisable as to all shares covered thereby, notwithstanding
anything to the contrary in Section 6.3 of this Plan or any installment
provisions of such Option.

9. Disqualifying Dispositions

         If a Participant makes a "disposition" (within the meaning of Code
Section 424(c)) of any shares issued upon exercise of an Incentive Stock Option
within two years after the date the Incentive Stock Option is granted or within
one year after shares are issued to the Participant pursuant to the exercise of
the Incentive Stock Option, the Participant shall notify the Committee in
writing of such disposition within 20 days thereafter.

                                      -7-
<PAGE>

10. No Rights as a Shareholder

         No Participant shall have any rights or privileges as a shareholder
with respect to any shares subject to Options prior to the date of issuance to
him or her of a certificate for such shares.

11. No Right to Continued Employment

         Neither this Plan nor any Option granted under this Plan shall confer
upon any Participant or any other person any right to continued employment by
the Company or any Subsidiary Corporation, nor shall it interfere in any way
with the right of his or her employer to terminate his or her employment at any
time for any reason whatsoever, with or without cause.

12. Compliance With Laws and Regulations

         This Plan, the grant and exercise of Options under this Plan and the
obligation of the Company to sell and deliver shares under Options shall be
subject to all applicable federal and state laws, rules and regulations and to
any approvals by any government or regulatory agency as may be required. The
Company shall not be required to issue or deliver any certificate for shares of
Stock either (a) prior to (i) the listing of such shares on any stock exchange
on which the Stock may then be listed or inclusion on any interdealer quotation
system on which the Stock may be quoted, and (ii) the completion of any
registration or qualification of such shares which is required under any federal
or state law, or any ruling or regulation of any government body, and which the
Company shall, in its sole discretion, determine to be necessary or advisable,
or (b) until exemptions from such registration and qualification requirements
are established to the reasonable satisfaction of the Company and its counsel.

13. Administration

         The Board may appoint a Stock Option Committee consisting of two or
more Directors to administer this Plan. The Committee members shall serve at the
pleasure of the Board. If the Board does not appoint a Committee, the Board
shall administer this Plan and shall have the powers and duties granted to the
Committee in this Plan.

         If Stock is registered under Section 12 of the Exchange Act, no
Director shall be appointed to, or shall serve on, the Committee unless he or
she shall be a "disinterested person" within the meaning of Rule 16b-3 under
such Act as presently in effect or hereafter amended.

                                      -8-
<PAGE>

         The Committee shall administer this Plan in accordance with its
provisions and shall have full authority to interpret this Plan, prescribe,
amend and rescind any rules and regulations necessary or appropriate for the
administration of this Plan and make such other determinations and take such
other action as it deems necessary or advisable, except as otherwise expressly
reserved to the Board in this Plan. Without limiting the generality of the
preceding sentence, the Committee may, in its discretion, determine that for
Option purposes a Participant remains an Employee during all or any portion of a
leave of absence approved by the Company. Any interpretation, determination or
other action made or taken by the Committee shall be final and binding upon all
Participants.

         No member of the Committee and no officer of the Company shall be
personally liable for any action, determination or interpretation made in good
faith with respect to this Plan or any Option, and all such persons shall be
fully indemnified and protected by the Company, to the full extent that the
Company is permitted to provide such indemnification and protection, in respect
to an such action, determination or interpretation.

14. Severability

         The invalidity or unenforceability of any particular provision of this
Plan shall not affect the other provisions, and this Plan shall be construed in
all respects as if any invalid or unenforceable provisions were omitted, but
only to the extent invalid or unenforceable under the circumstances.

15. Effective Date

         This Plan shall be effective as of the date of adoption by the Board.

16. Approval by Shareholders

         This Plan will be submitted for the approval by holders of a majority
of the shares of Stock voting thereon within twelve months after the Board's
adoption of this Plan. Options may be granted prior to such shareholder
approval, provided that such Options shall not be exercisable prior to the time
when the Plan is approved by shareholders and, if such approval is not obtained
by the end of the twelve-month period, all Options previously granted shall
thereupon be cancelled.

17. Amendment and Discontinuance

         The Board may from time to time amend, suspend or discontinue this
Plan; provided that, without approval of the holders of a majority of the shares
of Stock voting thereon, no action of the Board shall (a) increase the number of
shares reserved for Options pursuant to Section 3 of this Plan, (b) permit the
grant of any Option at a price less than that determined in accordance with
Section 6.2 of this Plan, or (c) permit the grant of Options which expire beyond
the periods provided for in Section 6.3 of this Plan. Without the written
consent of a Participant, no such amendment, suspension or discontinuance of
this Plan shall alter or impair any Option previously granted to such
Participant pursuant to this Plan.

                                      -9-
<PAGE>

18.      Term

         Unless terminated earlier pursuant to Section 17 of this Plan, this
Plan shall expire on, and no further Options shall be granted pursuant to this
Plan on or after, ten years after the date of adoption of this Plan by the
Board.

                                      -10-

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