Document:

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                                                                   Exhibit 10.57

                                 PROMISSORY NOTE
                                 ---------------

$500,000.00

1.      Promise to Pay.
        --------------

        For value received, I, Brian M. McNamee ("Staff Member"), a married man,
        and I, Gillian D. McNamee, wife of Staff Member, promise to pay to the
        order of Amgen Inc., a Delaware corporation ("Payee"), at its office at
        One Amgen Center Drive, Thousand Oaks, CA 91320-1789, the sum of Five
        Hundred Thousand Dollars and No Cents ($500,000.00) (the "Principal"),
        payable in full on the earlier of five (5) years from date of execution
        of this Note or thirty (30) days from the date on which Staff Member
        ceases to be an employee of Payee, whichever first occurs, together with
        interest on the Principal from the date of this Note until such date as
        the Note is paid in full. Interest on this Note shall be computed as set
        forth below. The interest rate for the period from the date of this Note
        through December 31, 2001 (the "initial rate") is 5.00% per annum on the
        unpaid Principal. After December 31, 2001 the interest rate on this Note
        shall change as set forth below.

2.      Adjustable Interest Rate.
        ------------------------

        The interest rate shall be adjusted annually on January 1 of each year
        (the "Change Date") so as to equal the average interest rate designated
        as the "Introduction Rates" on adjustable rate loans as publicly offered
        by the banks and savings and loans in California as published by the Los
        Angeles Times in its Sunday edition. The rate shall be set using the
        rates published in the Los Angeles Times on the Sunday immediately
        preceding the Change Date. In the event that the "Introduction Rates"
        list is not published in the Los Angeles Times for any reason, then, in
        such event, the Payee shall establish the interest rate based on a
        survey by it of the introductory interest rates on adjustable loans
        offered by no fewer than five banking institutions located in Southern
        California that the Payee, in its sole discretion, deems representative
        of banking institutions in the Ventura and Los Angeles County areas.
        Payee shall give Staff Member notice if the interest rate shall be
        determined using this alternative method. Notwithstanding the foregoing,
        the interest rate shall never be increased or decreased on any single
        Change Date by more than one percentage point from the interest rate for
        the preceding 12 months. At no time during the term of this Note shall
        the annual interest rate exceed 8.00% per annum.

        Payee shall deliver or mail to Staff Member a notice of any changes in
        the adjustable interest rate on this Note and the amount of the Staff
        Member's semi-monthly payroll deductions before the effective date of
        any change. The notice shall include information required by law to be
        given to Staff Member and also the title and telephone number of a
        person who shall answer any questions Staff Member may have regarding
        the notice.

3.      Salary Deduction.
        ----------------

        The interest on this Note shall be payable by semi-monthly deductions
        from Staff Member's salary. The amount of such deductions shall
        initially be One Thousand Forty-One Dollars and Sixty-Seven Cents
        ($1,041.67) per installment; provided, however, that the manner of
        payment of this Note shall not be limited to deductions from Staff
        Member's salary. The amount of such deductions shall be adjusted
        annually concurrently with any adjustment in the interest rate on this
        Note to ensure that interest to be incurred during the ensuing calendar
        year shall be paid in twenty-four (24) equal payments. The first such

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        installment shall be on 06/15/01; the second installment shall be on
        06/30/01; and each successive installment shall be on the fifteenth and
        last days of each successive month until the Principal is repaid. Payee
        shall give Staff Member at least seven (7) days advance notice of any
        adjustment in the amount of said payroll deductions. Staff Member
        acknowledges and agrees that by executing this Note, Staff Member agrees
        to the payroll deductions described in this Note.

4.      Option to Convert.
        -----------------

        At the end of the term of this Note, Staff Member shall have the option
        to seek to convert this loan to a loan amortized over an additional
        five-year period by executing a new Promissory Note at terms to be
        mutually agreed upon by Staff Member and Payee. In the event that Staff
        Member and Payee are unable to reach agreement on such terms, this Note
        shall become immediately due and payable.

5.      Prepayment.
        ----------

        Staff Member may prepay without penalty this Note in whole or in part at
        any time. Any and all payments or prepayments under this Note may be
        made by Staff Member to Payee at the following address (or such other
        address as it designates in writing to Staff Member):

                            AMGEN INC.
                            One Amgen Center Drive
                            Thousand Oaks, California 91320-1789

                            Attention:  Accounting Manager

6.      Attorneys' Fees.
        ---------------

        Staff Member agrees to pay all costs and expenses, including, without
        limitation, collection agency fees and expenses, reasonable attorneys'
        fees, costs of suit and costs of appeal, which Payee may incur in the
        exercise, preservation or enforcement of its right, powers and remedies
        hereunder, or under any documents or instruments securing this Note, or
        under law.

7.      Modification of Terms.
        ---------------------

        Payee may, with or without notice to Staff Member, cause additional
        parties to be added to this Note, or release any party to this Note, or
        revise, extend, or renew the Note, or extend the time for making any
        installment provided for by this Note, or accept any installment in
        advance, all without affecting the liability of Staff Member. Staff
        Member may not assign or transfer in any manner whatsoever this Note or
        any of Staff Member's obligations under this Note.

8.      Security Interest.
        -----------------

        The purpose of this loan is to purchase a personal residence. Staff
        Member shall secure this loan by executing and causing to be filed,
        immediately upon close of escrow, a trust deed on this residence,
        commonly known as 5921 Careybrook Drive, Agoura Hills, CA 91301 whose
        property description is as follows: Lot 79, of Tract No. 33411, in the
        City of

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        Agoura Hills, County of Los Angeles, State of California, as per map
        recorded in Book 1022 Page(s) 7 - 15 inclusive of Maps, in the office of
        the County Recorder of said County.

9.      Acceleration.
        ------------

        A) In the event Staff Member fails to pay when due any sums under this
        Note, then:

           (1) the entire unpaid balance of this Note shall, at the option of
           the Payee hereof, immediately become due and payable in full and
           unpaid Principal thereafter shall bear interest at the lesser of the
           maximum rate permitted by law or at the rate of 8.00% per annum; and

           (2) Staff Member authorizes Payee to deduct any sums due to Payee
           under this Note from any monies, including any wages due, otherwise
           owing to Staff Member.

        B) If Staff Member sells the residence which is purchased with the funds
        herein provided, this Note shall immediately become due and payable upon
        the sale of such residence.

10.     Waiver of Rights by Staff Member.
        --------------------------------

        Staff Member waives (1) presentment, demand, protest, notice of dishonor
        and/or protest and notice of non-payment; (2) the right, if any, to the
        benefit of, or to direct the application of, any security hypothecated
        to Payee until all indebtedness of Staff Member to Payee, however
        arising, has been paid; and (3) the right to require the Payee to
        proceed against any party to this Note, or to pursue any other remedy in
        Payee's power. Payee may proceed against Staff Member directly and
        independently of any other party to this Note, and the cessation of the
        liability of any other party for any reason other than full payment, or
        any revision, renewal, extension, forbearance, change of rate of
        interest, or acceptance, release or substitution of security, or any
        impairment or suspension of Payee's remedies or rights against any other
        party, shall not in any way affect the liability of Staff Member.

11.     Obligations of Persons Under this Note.
        --------------------------------------

        If more than one person signs this Note, each person is fully and
        personally obligated to keep all of the promises made in this Note,
        including the promise to pay the full amount owed. Any person who is a
        guarantor, surety, or endorser of this Note is also obligated to do
        these things. Any person who takes over these obligations, including the
        obligations of a guarantor, surety or endorser of this Note, is also
        obligated to keep all of the promises made in this Note. Payee may
        enforce its rights under this Note against each person individually or
        against all of the signatories to this Note. This means that any one of
        the signatories to this Note may be required to pay all of the amounts
        owed under this Note.

12.     Governing Law.
        -------------

        This Note and the obligations under this Note of Staff Member or any
        other signatory to this Note shall be governed by and interpreted and
        determined in accordance with the laws of the State of California as
        applied to contracts between California residents entered into and to be
        performed entirely within said State.

<PAGE>

IN WITNESS WHEREOF, the undersigned has/have executed and delivered this Note as
of the 30th day of May, 2001.

                                          /s/ Brian M. McNamee
                                          ______________________________________
                                          Brian M. McNamee

                                          /s/ Gillian D. McNamee
                                          ______________________________________
                                          Gillian D. McNamee<PAGE>

                                                                   Exhibit 10.58

                       RESTRICTED STOCK PURCHASE AGREEMENT

RICHARD NANULA, Amgen Inc. Grantee:

          On this 16th day of May, 2001, Amgen Inc., a Delaware corporation (the
"Company"), pursuant to its Amended and Restated 1991 Equity Incentive Plan (the
"Plan") has granted to you, the grantee named above, a right to purchase Eighty
Five Thousand (85,000) shares (the "Shares") of the $.0001 par value common
stock of the Company ("Common Stock") pursuant to the terms of this Restricted
Stock Purchase Agreement (this "Agreement") and the Plan. Capitalized terms not
defined herein shall have the meanings assigned to such terms in the Plan.

          I.   Purchase Price. Subject to the terms and conditions of this
               --------------
Agreement, the Shares may be purchased from the Company at a purchase price per
share of $.0001 for a total purchase price of $8.50 (the "Total Purchase
Price"). The Total Purchase Price shall be paid in cash at the time of purchase.

          II.  Repurchase Option.
               -----------------

               (1)  Subject to Section III(4), upon termination of your
employment for any reason, other than death and permanent and total disability
(with such permanent and total disability being certified by the Social Security
Administration prior to such termination), the Company shall have the right and
option to purchase from you or any holder of the Shares as permitted under
Section III(5) (a "Holder") any or all of the Shares at the per Share purchase
price paid by you for such Shares (the "Repurchase Option").

               (2)  The Company may exercise the Repurchase Option by delivering
personally or by registered mail, to you or a Holder within ninety (90) days of
the date of termination of your employment, a notice in writing indicating the
Company's intention to exercise the Repurchase Option and setting forth a date
for closing not later than thirty (30) days from the mailing of such notice. The
closing shall take place at the Company's office. At the closing, the Secretary
of the Company or other escrow agent as provided in Section VI shall deliver the
stock certificate or certificates evidencing the Shares to the Company, and the
Company shall deliver the purchase price therefor to you or a Holder.

               (3)  At its option, the Company may elect to make payment for the
Shares to a bank selected by the Company. The Company shall avail itself of this
option by a notice in writing to you or a Holder stating the name and address of
the bank, date of closing, and waiving the closing at the Company's office.

               (4)  If the Company does not elect to exercise the Repurchase
Option conferred above by giving the requisite notice to you or a Holder within
ninety (90) days following the date of termination of your employment, the
Repurchase Option shall terminate, and any restrictions on Shares remaining as
of the date of the termination of your employment shall lapse immediately.

<PAGE>

               (5)  One hundred percent (100%) of the Shares shall initially be
subject to the Repurchase Option. The Shares shall be released from the
Repurchase Option in accordance with the schedule set forth in Section III(1).

          III. Lapse of Repurchase Option.
               --------------------------

               (1)  Subject to Sections III (2), (3) and (4), the Repurchase
Option shall lapse in accordance with the following schedule with respect to the
Shares which have not previously been forfeited by you, provided you are
actively employed by the Company on the respective dates:

                                   Number of Shares to Which Repurchase Option
                                   -------------------------------------------
                   Date                          Shall Lapse
                   ----                          -----------
               May 16, 2004                         20,000
               May 16, 2005                         20,000
               May 16, 2006                         45,000

               (2)  Upon termination of your employment due to your permanent
and total disability (with such permanent and total disability being certified
by the Social Security Administration prior to such termination) or your death,
then the Repurchase Option shall lapse immediately with respect to all the
Shares awarded under this Agreement. For purposes of this Agreement,
"termination of your employment" shall mean the last date you are either an
employee of the Company or an Affiliate or engaged as a consultant or director
to the Company or an Affiliate.

               (3)  In addition, the lapsing of the Repurchase Option pursuant
to Section III(1) may be suspended during a leave of absence as provided from
time to time according to Company policies and practices.

               (4)  Upon termination of your employment by Amgen without Cause,
the Repurchase Option shall automatically lapse with respect to a pro rata
portion of each tranche of restricted stock for which the Repurchase Option was
otherwise scheduled to lapse as set forth in Section III(1), multiplied by the
ratio of (x) the sum of the number of full months of your active employment with
the Company and (y) the number of months otherwise required for lapsing of the
Repurchase Option with respect to such tranche, as follows:

               Number of Shares                   Ratio
               ----------------                   -----
                    20,000           x            Z/36
                    20,000           x            Z/48
                    45,000           x            Z/60

where Z= the sum of the number of full months of your active employment with the
Company.

               Solely for the purpose of this Agreement, "Cause" means (i) your
conviction of a felony, (ii) the engaging by you in conduct that constitutes
willful gross neglect

                                       2

<PAGE>

or willful gross misconduct in carrying out your duties to the Company,
resulting, in either case, in material economic harm to the Company, unless you
believed in good faith that such conduct was in, or not contrary to, the best
interests of the Company, (iii) your material breach of any of the terms of this
letter agreement or the Proprietary Information and Inventions Agreement or (iv)
your failure to follow any lawful directive of the Company's Chief Executive
Officer with respect to your employment. For purposes hereof, no act, or failure
to act, on your part shall be deemed "willful" unless done, or omitted to be
done, by you not in good faith.

               Notwithstanding anything to the contrary contained herein, the
Committee may, as it deems appropriate, in its sole discretion, accelerate the
date on which the Repurchase Option shall lapse with respect to any of the
Shares which have not been previously forfeited by you.

               (5)  Your Shares are not assignable or transferable, except by
will or the laws of descent and distribution. Notwithstanding the foregoing, all
or a portion of the Shares subject to the Repurchase Option may be transferred
to an Alternate Payee (as defined in the Plan) if required by the terms of a
QDRO (as defined in the Plan), as further described in the Plan; provided, that
such Alternate Payee is subject to the same terms and conditions as set forth in
this Agreement

          IV.  Legends. Certificates representing the Shares issued pursuant to
               -------
this Agreement shall, until all restrictions lapse or shall have been removed
and new certificates are issued pursuant to Section V, bear the following
legend:

     "THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO
     CERTAIN RESTRICTIONS AND REPURCHASE RIGHTS AND MAY BE SUBJECT TO
     FORFEITURE UNDER THE TERMS OF THAT CERTAIN RESTRICTED STOCK PURCHASE
     AGREEMENT BY AND BETWEEN AMGEN INC. (THE "COMPANY") AND THE
     REGISTERED OWNER OF SUCH SHARES, AND SUCH SHARES MAY NOT BE, DIRECTLY
     OR INDIRECTLY, OFFERED, TRANSFERRED, SOLD, ASSIGNED, PLEDGED,
     HYPOTHECATED OR OTHERWISE DISPOSED OF UNDER ANY CIRCUMSTANCES, EXCEPT
     PURSUANT TO THE PROVISIONS OF SUCH AGREEMENT."

          V.   Issuance of Certificates; Tax Withholding.
               -----------------------------------------

               (1)  Subject to subsection (2) below, upon the lapse of the
Repurchase Option with respect to any of the Shares as provided in Section III,
the Company shall cause new certificates to be issued with respect to such
Shares and delivered to you or a Holder, free from the legend provided for in
Section IV and of the Repurchase Option. Such Shares shall cease to be subject
to the terms and conditions of this Agreement.

               (2)  Notwithstanding subsection (1), no such new certificate
shall be delivered to you or a Holder unless and until you or a Holder shall
have paid to the Company, in cash or by check, the full amount of all federal
and state withholding or other employment taxes applicable to your taxable
income resulting from the grant of the Shares or the lapse or removal of the
restrictions in a form approved by the Committee.

                                       3

<PAGE>

               VI.    Escrow. The Secretary of the Company or such other escrow
                      ------
holder as the Committee may appoint shall retain physical custody of the
certificates representing the Shares until all of the restrictions lapse or
shall have been removed, including, without limitation, the Repurchase Option.

               VII.   No Contract for Employment. This Agreement is not an
                      --------------------------
employment or service contract and nothing in this Agreement shall be deemed to
create in any way whatsoever any obligation on your part to continue in the
employ or service of the Company, or of the Company to continue your employment
or service with the Company.

               VIII.  Notices. Any notices provided for in this Agreement or the
                      -------
Plan shall be given in writing and shall be deemed effectively given upon
receipt or, in the case of notices delivered by the Company to you, five (5)
days after deposit in the United States mail, postage prepaid, addressed to you
at such address as is currently maintained in the Company's records or at such
other address as you hereafter designate by written notice to the Company.

               IX.    Plan. This Agreement is subject to all the provisions of
                      ----
the Plan and its provisions are hereby made a part of this Agreement, including
without limitation the provisions of paragraph 7 of the Plan relating to
purchases of restricted stock, and is further subject to all interpretations,
amendments, rules and regulations which may from time to time be promulgated and
adopted pursuant to the Plan. In the event of any conflict between the
provisions of this Agreement and those of the Plan, the provisions of the Plan
shall control.

                             Very truly yours,
                             AMGEN INC.

                             By  /s/ Steven M. Odre
                                ____________________________________
                             Duly authorized on behalf of the Board of Directors

Agreed and Accepted
as of the date first written above

/s/ Richard Nanula
_________________________________
Richard Nanula

                                       4

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