<PAGE>

                                                                   Exhibit 10.52
                                PROMISSORY NOTE
                                ---------------


$1,000,000.00


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

    For value received, I, Roger M. Perlmutter ("Staff Member"), a married man,
    and I, Joan Kreiss, wife of Staff Member,  and the PERLMUTTER-KREISS
    REVOCABLE LIVING TRUST, a Revocable Living Trust, jointly and severally,
    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 One Million Dollars and No Cents ($1,000,000.00) (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 Two
    Thousand Eighty-Three Dollars and Thirty-Three Cents ($2,083.33) 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 installment shall be on 07/15/01; the second
    installment shall be on 07/31/01; 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
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    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 755
    El Bosque Road, Santa Barbara, CA  93108 whose property description is as
    follows:  legal description attached hereto and made a part hereof.

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
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    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.

IN WITNESS WHEREOF, the undersigned has/have executed and delivered this Note as
of the 29 day of June, 2001.
       --        ----

/s/ Roger M. Perlmutter                PERLMUTTER-KREISS REVOCABLE
------------------------               LIVING TRUST
    Roger M. Perlmutter                A Revocable Living Trust


                                       ----------------------------------
/s/ Joan Kreiss                        By: /s/ Joan Kreiss
--------------------------             ----------------------------------
    Joan Kreiss                        Title: Trustee