Document:

<PAGE>

                                                                   EXHIBIT 10.16

                        AMENDMENT AND TRANSFER AGREEMENT

              PLAINS RESOURCES INC. 401(k) PLAN AND TRUST AND THE

                   PLAINS ALL AMERICAN 401(k) PLAN AND TRUST

          THIS AGREEMENT by Plains Resources Inc., a Delaware corporation (the
"Sponsor"), Plains All American Inc., a Delaware corporation (the "Employer"),
and Plains All American GP LLC, a Delaware limited liability company (the
"Company"),

                              W I T N E S S E T H:
                              - - - - - - - - - -

          WHEREAS, the Sponsor previously established the Plains Resources Inc.
401(k) Plan for the benefit of its eligible employees and their beneficiaries
(the "Plan");

          WHEREAS, the Plan provides that any business organization may, with
the approval of the Sponsor, adopt the Plan for all or any classification of its
employees;

          WHEREAS, the Employer previously adopted the Plan for the benefits of
its eligible employees and their beneficiaries;

          WHEREAS, the Company shall establish the Plains All American 401(k)
Plan for the benefit of its eligible former employees and their beneficiaries
(the "PAA Plan");

          WHEREAS, in connection with the transactions contemplated by multiple
Unit Transfer and Contribution Agreements, dated as of May 8, 2001 or
thereafter, each as amended from time to time (collectively, the "Contribution
Agreement"), prior to the Closing Date of the Contribution Agreement, all of the
property used in the trade or business of the Employer as general partner of
Plains All American Pipeline, L.P. (the "MLP") will be transferred to the
Company;

          WHEREAS, in connection with the Contribution Agreement, the Company
will succeed to the management and business activities formerly performed by the
Employer;
<PAGE>

          WHEREAS, in connection with the Contribution Agreement, the Sponsor,
the Employer and the Company will enter into a Pension and Employee Benefits
Assumption and Transition Agreement, effective as of June 8, 2001 (the
"Transition Agreement"); and

          WHEREAS, the Sponsor, the Employer and the Company have agreed to
transfer certain assets and liabilities from the Plan and the Plains Resources
Inc. 401(k) Trust (the "Trust") to the PAA Plan and the Plains All American
401(k) Trust (the "PAA Trust") which represent 100 percent of the account
balances of Transferred Employees, as defined in the Transition Agreement, who
are participants in the Plan on the last day of the Transition Period, as
defined in the Transition Agreement (the "Plan Participants");

          NOW, THEREFORE, effective as of the last day of the Transition Period,
as defined in the Transition Agreement (the "Transfer Date"), the parties agree
as follows:

          (1) As soon as practicable after the date hereof, the Company agrees
     to establish or designate, and maintain the PAA Plan, a defined
     contribution plan, to provide benefits to the Plan Participants which are
     substantially equivalent to the benefits provided to participants under the
     Plan (provided, however, that all matching contributions will be paid in
     cash).  The PAA Plan shall be qualified under sections 401(a) and 401(k) of
     the Internal Revenue Code of 1986, as amended (the "Code") and shall
     provide the Plan Participants credit for service with the Sponsor and its
     affiliates (including the Employer) and their respective predecessors prior
     to the Transfer Date for all purposes for which service was recognized
     under the Plan.

          (2) As soon as practicable after the filing of the determination
     letter request described in paragraph (3) below, the Sponsor shall cause
     Wells Fargo Bank (Texas), N.A. ("Wells Fargo"), as trustee of the Trust, to
     transfer to the PAA Trust cash or assets in which the Plan Participants are
     currently invested (or with respect to participant loans granted prior to
     the Transfer Date, if any, such loans and any promissory notes or other
     documents evidencing such loans) in an amount equal to the account balances
     of Plan Participants as of a valuation date (the "Valuation Date") not more
     than 60 days preceding the date of transfer, increased by any contributions
     due for periods prior to and including the Transfer Date and not made as of
     the Valuation Date, reduced by any benefits paid during the period
     following such Valuation Date to the Transfer Date, and adjusted for any
     investment earnings or losses during the period following such Valuation
     Date to the Transfer Date (the "Transferred Assets").  All Section
     411(d)(6) protected benefits attributable to the Transferred Assets shall
     continue to be available under the PAA Plan.  The Sponsor, the Employer,
     the Plan, the Company and the PAA Plan hereby agree to comply with all
     requirements under the Employee Retirement Income Security Act of 1974, as

                                       2
<PAGE>

     amended, and the Code, including but not limited to section 411 of the
     Code, that are applicable to such transfers.

          (3)  No later than 60 days after the Transfer Date, the Company shall
     file a request for a determination letter with the Internal Revenue Service
     (the "IRS") that the PAA Plan and Trust satisfy the requirements for
     qualification under sections 401(a) and 401(k) of the Code.  The Company
     agrees that it shall amend the PAA Plan in any respect as may be required
     by the IRS in order to receive a favorable determination letter from the
     IRS that the PAA Plan and Trust satisfy the requirements for qualification
     under sections 401(a) and 401(k) of the Code.  No transfer shall be made
     until the Company files with the IRS the request for determination letter
     referred to in this paragraph (3).

          (4)  This Agreement may be executed in any number of counterparts,
     each of which shall be deemed an original, but all of which will constitute
     one and the same Agreement and will be binding on the respective successors
     and assigns of the parties.

          IN WITNESS WHEREOF, the parties have caused this Agreement to be
executed this 8th day of June 2001.

                                 PLAINS RESOURCES INC.

                                 By   /s/ JAMES C. FLORES
                                   ----------------------
                                 Title Chairman and Chief Executive Officer
                                      --------------------------------------

                                 PLAINS ALL AMERICAN INC.

                                 By   /s/ GREG L. ARMSTRONG
                                   ------------------------
                                 Title  Chief Executive Officer
                                      -------------------------

                                 PLAINS ALL AMERICAN GP LLC  by
                                 PLAINS ALL AMERICAN INC., its Sole
                                 Member

                                 By   /s/ GREG L. ARMSTRONG
                                   ------------------------
                                 Title  Chief Executive Officer
                                      -------------------------

                                       3<PAGE>
                                                                    EXHIBIT 10.1

                                AMENDMENT NO. 1
                                       TO
                 2000 NON-EMPLOYEE DIRECTORS' STOCK OPTION PLAN

     THIS AMENDMENT by Tanox, Inc. (the "Company"),

WITNESSETH:
-----------

     WHEREAS, the Company maintains the Tanox, Inc. 2000 Non-Employee Directors'
Stock Option Plan (the "Plan"); and

     WHEREAS, the Company retained the right in Section 12 of the Plan for the
Board of Directors of the Company to amend the Plan from time to time; and

     WHEREAS, the Board of Directors approved resolutions on May 16, 2001,
amending the Plan as set forth below;

     NOW, THEREFORE, the Company agrees that, effective June 1, 2001, the plan
is amended as follows, subject in all respects to the approval hereof by the
stockholders of the Company at the annual meeting of stockholders to be held in
2002 and no Option awarded hereunder may be exercised unless and until such
approval is granted:

     1.   Section 2 of the Plan is hereby amended to include the following new
          definition:

          "Black Scholes Value" means the value of an Option using the Black-
          Scholes valuation methodology determined either as of the date of the
          relevant grant of the Option or as used to value the most recent stock
          option grant made within the preceding twenty-four months under this
          or any other stock option plan of the Company.  The assumptions used
          to determine the Black Scholes Value and the date of valuation will be
          subject to approval by the Board.

     2.   Section 5 of the Plan is hereby amended to read as follows in its
          entirety:

     "5.  ELIGIBILITY.

          All Non-Employee Directors shall be eligible to participate in the
          Plan."

      3.  Section 6 of the Plan is hereby amended to read as follows in its
          entirety:

     "6.  NON-DISCRETIONARY GRANTS.

        (a) Initial Grant. After May 16, 2001, each person who is elected or
     appointed to be a Non-Employee Director for the first time automatically
     shall, upon
<PAGE>

     the date of his or her election or appointment, be granted an Option to
     purchase shares of Common Stock having a Black Scholes Value of $200,000 on
     the terms and conditions set forth herein.

        (b) Subsequent Grant. Beginning with the 2002 annual meeting of
     stockholders, each person who is a Non-Employee Director immediately
     following any annual meeting of stockholders of the Company at which
     Directors are elected, and who has not received a grant under Section 6(a)
     within the preceding six months, shall automatically be granted, on the
     date of such annual meeting, an Option to purchase shares of Common Stock
     having a Black Scholes Value of $80,000 on the terms and conditions set
     forth herein."

        IN WITNESS WHEREOF, the Company has executed this Amendment this 16th
day of May, 2001.

                                        TANOX, INC.

                                        By:   Michael A. Kelly
                                           ----------------------------------
                                        Name:  Michael A. Kelly
                                        Title: Vice President and CFO

                                       2

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00028-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00028-of-00352.parquet"}]]