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                                                                   Exhibit 10.37

                                 PROMISSORY NOTE

South San Francisco, California                                         $215,000

July 12, 2002

     FOR VALUE RECEIVED, the undersigned Jay Trautman ("BORROWER") hereby
promises to pay to the order of Cytokinetics, Incorporated, a Delaware
corporation ("LENDER" also known as "Cytokinetics") at 280 East Grand Avenue,
South San Francisco, California (or at such other address as the holder of this
NOTE may designate by notice to BORROWER), in lawful money of the United States
of America, the sum of Two Hundred Fifteen Thousand Dollars ($215,000), as set
forth below.

     1.     Definitions.

                  a.       "INTEREST RATE" shall mean the PRIME RATE plus 1%,
                           which sum is equal to 5.75% per annum.

                  b.       "SHARES" shall mean the options to purchase 125,000
                           shares of Common Stock of the LENDER presently held
                           by BORROWER and the shares of Common Stock of the
                           LENDER to be acquired by BORROWER upon exercise of
                           such options that will secure payment hereunder.

                  c.       "DUE DATE" shall mean the earliest of any of the
                           following:

                           (i)    the sale, conveyance, alienation, assignment,
                                  pledge, grant of any lien or other transfer by
                                  BORROWER of any of the SHARES without the
                                  prior written consent of the LENDER;

                           (ii)   ninety (90) days after TERMINATION OF
                                  EMPLOYMENT;

                           (iii)  eighteen (18) months after a LIQUIDITY EVENT;
                                  or

                           (iv)   such earlier date as may be required by LENDER
                                  upon acceleration of the DUE DATE in
                                  accordance with Section 5 of this NOTE.

                  d.       "TERMINATION OF EMPLOYMENT" shall mean the voluntary
                           or involuntary termination of BORROWER's employment
                           relationship with LENDER for any reason or no reason,
                           with or without cause.

                  e.       "LIQUIDITY EVENT" shall mean (i) an acquisition of
                           the LENDER in which the stockholders of the LENDER
                           receive cash or publicly traded securities in
                           exchange for their shares of stock of the LENDER, or
                           (ii) the

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                           first public offering by the LENDER of shares of its
                           capital stock pursuant to a registration statement on
                           Form S-1 under the Securities Act of 1933.

                  f.       "PRIME RATE" shall mean an interest rate equal to the
                           interest rate announced by the Federal Reserve Bank
                           of San Francisco as its prime rate as of the date of
                           this NOTE.

     2.     Payments.

                  a.       Commencing on the date hereof, interest on the unpaid
                           principal balance of this NOTE shall accrue at the
                           INTEREST RATE.

                  b.       The NOTE shall be repayable according to the
                           following schedule:

                           (i)    On the first anniversary of this NOTE, all
                                  interest accrued under this NOTE to such date;

                           (ii)   On the second anniversary of this NOTE, all
                                  interest accrued under this NOTE to such date;

                           (iii)  20% of the original principal balance of this
                                  NOTE on the third anniversary of this NOTE,
                                  plus all interest accrued under this NOTE to
                                  such date;

                           (iv)   20% of the original principal balance of this
                                  NOTE on the fourth anniversary of this NOTE,
                                  plus all interest accrued under this NOTE to
                                  such date;

                           (v)    20% of the original principal balance of this
                                  NOTE on the fifth anniversary of this NOTE,
                                  plus all interest accrued under this NOTE to
                                  such date; and

                           (vi)   40% of the original principal balance of this
                                  NOTE on the sixth anniversary of this NOTE,
                                  plus all interest accrued under this NOTE to
                                  such date.

                           Notwithstanding the foregoing, all principal and
                           accrued interest on the principal balance of this
                           NOTE shall be due and payable on the DUE DATE.

                  g.       All payments shall be applied first against accrued
                           interest, and secondly against principal.

     3.     Prepayment.

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         BORROWER may prepay all or any portion of the principal on this NOTE
         and the accrued interest without penalty or acceleration of the DUE
         DATE of this NOTE.

     4.     Security/Insurance.

         This NOTE is secured by a pledge of the SHARES under the terms of a
         SECURITY AGREEMENT, substantially in the form attached hereto as
         Exhibit A (the "SECURITY AGREEMENT") and dated as of even date hereof,
         and is subject to all of the provisions thereof.

     5.     Acceleration of DUE DATE.

         The entire unpaid principal of this NOTE and accrued interest thereon
         shall at the election of the LENDER, become immediately due and payable
         upon the occurrence of any of the following, irrespective of the DUE
         DATE as otherwise defined in this NOTE:

                  a.       BORROWER fails to make any payment when the same is
                           due;

                  b.       BORROWER fails to perform or observe any of the
                           covenants or obligations of BORROWER set forth in
                           this NOTE or contained in the SECURITY AGREEMENT for
                           a period of ten (10) days after written notice
                           thereof from LENDER;

                  c.       A bankruptcy or insolvency proceeding is instituted
                           by or against BORROWER, or if a receiver is appointed
                           for the property of BORROWER; or

                  d.       BORROWER makes an assignment for the benefit of
                           creditors.

     6.     Collection Costs Borne by BORROWER.

         In the event of any failure on the part of BORROWER to make any payment
         when the same is due, LENDER shall be entitled to recover from BORROWER
         all costs of effecting collection of the same, including reasonable
         attorneys' fees. Unpaid principal and interest subject to collection
         shall bear interest at the maximum rate allowed under California law
         for nonexempt lenders.

     7.     Certification of BORROWER.

         So long as the NOTE shall remain outstanding, BORROWER shall not sell,
         assign, transfer, convey, pledge, or grant a lien against the SHARES.
         In the event of any involuntary (by act of law or otherwise) sale,
         conveyance, pledge, lien, alienation or other transfer by BORROWER of
         any of the SHARES, BORROWER shall immediately notify LENDER.

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         BORROWER also warrants that, upon the written request of LENDER,
         BORROWER shall deliver to LENDER a written confirmation that a sale,
         conveyance, pledge, lien, alienation or other transfer of the SHARES
         has not occurred.

     8.     Full Recourse.

         The holder of this NOTE shall have full recourse against the BORROWER,
         and shall not be required to proceed against the collateral securing
         the NOTE pursuant to the SECURITY AGREEMENT in the event of the
         occurrence of an event set forth in Section 5 of this NOTE.

     9.     No Right to Continued Employment.

         Nothing contained herein shall be construed to confer on BORROWER any
         right to continued employment with the LENDER.

     10.    Governing Law.

         This NOTE shall be governed by and construed in accordance with the
         internal laws of the State of California. BORROWER consents to personal
         jurisdiction in any court in San Mateo County, California.

     11.    Successors.

         This NOTE shall be binding upon and shall inure to the benefit of the
         parties hereto and their respective representatives, heirs,
         administrators, successors and assigns.

Effective as of the date set forth above.

BORROWER:

         /s/ Jay Trautman
__________________________________________

Name:           Jay Trautman
     _____________________________________

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ACCEPTED AND ACKNOWLEDGED:

LENDER:

CYTOKINETICS, INCORPORATED, a Delaware corporation

By: /s/ James Sabry
   -------------------------------------
Name:
      ----------------------------------
Title:
       ---------------------------------
By: /s/ Robert Blum
    ------------------------------------
Name: Robert I. Blum
      ----------------------------------
Title: SVP. Corp. Dev. & Finance & CFO
       ---------------------------------

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                                    EXHIBIT A

                               SECURITY AGREEMENT

         This Security Agreement is made as of July 12, 2002 between
Cytokinetics, Incorporated, a Delaware corporation ("Pledgee"), Jay Trautman
("Pledgor"), and Secretary of Pledgee, as the agent of Pledgee and holder of the
Collateral, as defined below, pledged hereunder ("Pledgeholder").

                                    Recitals

         Pursuant to the Promissory Note dated July 12, 2002 (the "Note"),
between Pledgor and Pledgee, the Pledgee has loaned to Pledgor the principal
amount of $215,000 (the "Loan").

         NOW, THEREFORE, it is agreed as follows:

         1. Creation and Description of Security Interest. In consideration of
the Loan, Pledgor, pursuant to the California Uniform Commercial Code, hereby
pledges 125,000 shares of Common Stock of the Pledgee presently owned by Pledgor
which shall to the maximum extent permitted consist at all times of vested
shares (i.e. shares that are not subject to Pledgee's repurchase option) (herein
sometimes referred to as the "Collateral") and herewith delivers any
certificates currently held by Pledgor representing such Collateral to
Pledgeholder, who shall hold said certificates on behalf of Pledgee subject to
the terms and conditions of this Security Agreement.

         The Collateral (together with an executed blank stock assignment or
assignments in substantially the form attached hereto as Annex 1) shall be held
by Pledgeholder on behalf of Pledgee as security for the repayment of the Note,
and any extensions or renewals thereof, to be executed by Pledgor pursuant to
the terms of the Note, and Pledgeholder shall not sell, assign, transfer,
pledge, encumber or dispose of such Collateral except in accordance with the
provisions of this Security Agreement.

         2. Pledgor's Representations and Covenants. To induce Pledgee to enter
into this Security Agreement, Pledgor represents and covenants to Pledgee, its
successors and assigns, as follows:

                  (a) Payment of Indebtedness. Pledgor will pay the principal
sum of the Note secured hereby, and interest thereon, at the time and in the
manner provided in the Note.

                  (b) Encumbrances. The Collateral is free of all other adverse
claims, encumbrances, defenses and liens (other than restrictions on transfer
imposed by applicable securities laws), except for (i) Pledgee's rights to
repurchase the Collateral in connection with the termination of Pledgor's
service relationship with the Pledgee, (ii) the pledge of the Collateral
hereunder as security for payment of the Note, and (iii) the pledge of the
Collateral as security for payment of other obligations between the Pledgor and
Pledgee, and Pledgor will not further encumber the Collateral without the prior
written consent of Pledgee.

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         3. Voting Rights. During the term of this pledge and so long as all
payments of principal and interest are made as they become due under the terms
of the Note, Pledgor shall have the right to vote all of the Collateral pledged
hereunder.

         4. Stock Adjustments. In the event that during the term of the pledge
any stock dividend, reclassification, readjustment or other changes are declared
or made in the capital structure of Pledgee, all new, substituted and additional
shares or other securities issued by reason of any such change shall be
delivered to and held by the Pledgee under the terms of this Security Agreement
in the same manner as the Collateral originally pledged hereunder. In the event
of substitution of such securities, Pledgor, Pledgee and Pledgeholder shall
cooperate and execute such documents as are reasonable so as to provide for the
substitution of such Collateral and, upon such substitution, references to
"Collateral" in this Security Agreement shall include the substituted investment
property of Pledgor as a result thereof.

         5. Options and Rights. In the event that, during the term of this
pledge, subscription options or other rights or options shall be issued in
connection with the pledged Collateral, such rights and options shall be the
property of Pledgor and, if exercised by Pledgor, all new stock or other
securities so acquired by Pledgor as it relates to the pledged Collateral then
held by Pledgeholder shall be immediately delivered to Pledgeholder, to be held
under the terms of this Security Agreement in the same manner as the Collateral
pledged.

         6. Default. Pledgor shall be deemed to be in default of the Note and of
this Security Agreement in the event:

                  (a) Payment of principal or interest on the Note becomes
delinquent; or

                  (b) Pledgor fails to perform or observe any of the covenants
or obligations of Pledgor set forth in the Note or contained in this Security
Agreement for a period of 10 days after written notice thereof from Pledgee; or

                  (c) A bankruptcy or insolvency proceeding is instituted by or
against Pledgor, or if a receiver is appointed for the property of Pledgor; or

                  (d) Pledgor makes an assignment for the benefit of creditors.

         In the case of a default, as set forth above, Pledgee shall have the
right to accelerate payment of the Note, and Pledgee shall thereafter be
entitled to pursue its remedies under the California Uniform Commercial Code.

         7. Withdrawal or Substitution of Collateral. Pledgor shall not sell,
assign, transfer, withdraw, pledge, substitute or otherwise dispose of all or
any part of the Collateral without the prior written consent of Pledgee.

         8. Term. The within pledge of Collateral shall continue until the
payment of all indebtedness secured hereby.

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         9. Insolvency. Pledgor agrees that if a bankruptcy or insolvency
proceeding is instituted by or against Pledgor, or if a receiver is appointed
for the property of Pledgor, or if Pledgor makes an assignment for the benefit
of creditors, the entire amount unpaid on the Note shall become immediately due
and payable, and Pledgee may proceed as provided in the case of default.

         10. Pledgeholder Liability.

                  (a) Pledgeholder shall not be liable to any party for any of
its acts, or omissions to act, as Pledgeholder unless Pledgeholder is proved to
have acted in bad faith. Any act done or omitted pursuant to the advice of legal
counsel, other than an act or omission involving gross or willful negligence,
shall be deemed to be done or omitted in good faith.

                  (b) Pledgeholder shall be entitled to employ such legal
counsel and other experts as Pledgeholder may deem necessary to properly advise
Pledgeholder in connection with its obligations hereunder, and Pledgeholder may
rely upon the advice of such counsel. Such counsel's reasonable fees and costs
shall be borne 50% by Pledgor and 50% by Pledgee.

                  (c) It is understood and agreed that should any dispute arise
with respect to the delivery and/or ownership or right of possession of the
securities held by Pledgeholder hereunder, Pledgeholder is authorized and
directed to retain in Pledgeholder's possession as agent of Pledgee without
liability to anyone all or any part of said securities until such disputes shall
have been settled either by mutual written agreement of the parties concerned or
by a final order, decree or judgment of arbitration or of a court of competent
jurisdiction after the time for appeal has expired and no appeal has been
perfected, but Pledgeholder shall be under no duty whatsoever to institute or
defend any such proceedings.

         In addition, upon any dispute Pledgeholder should be entitled to engage
legal counsel, one-half of whose fees and expenses shall be borne by Pledgor and
one-half by Pledgee.

         11. Invalidity of Particular Provisions. Pledgor and Pledgee agree that
the enforceability or invalidity of any provision or provisions of this Security
Agreement shall not render any other provision or provisions herein contained
unenforceable or invalid.

         12. Successors or Assigns. Pledgor and Pledgee agree that all of the
terms of this Security Agreement shall be binding on their respective successors
and assigns, and that the term "Pledgor" and the term "Pledgee" as used herein
shall be deemed to include, for all purposes, the respective designees,
successors, assigns, heirs, executors and administrators.

         13. Governing Law. This Security Agreement shall be interpreted and
governed under the laws of the State of California.

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         IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the day and year first above written.

      "PLEDGOR"                                By:  ____________________________
                                                    Name: ______________________

                                                    ____________________________
                                                    Address

      "PLEDGEE"                                     Cytokinetics, Incorporated,
                                                    a Delaware corporation

                                                    By: ________________________

                                                    Title: _____________________

      "PLEDGEHOLDER"
                                                    ____________________________
                                                    Secretary of Pledgee

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                                    ANNEX 1

                           STOCK POWER AND ASSIGNMENT

                            SEPARATE FROM CERTIFICATE

         FOR VALUE RECEIVED and pursuant to that certain Security Agreement
dated as of ___________________, 200__ the undersigned hereby sells, assigns and
transfers unto ___________________________________________________, shares of
the Common Stock of Cytokinetics, Incorporated, a Delaware corporation (the
"Company"), standing in the undersigned's name on the books of the Company
represented by Certificate No. _____ delivered herewith, and does hereby
irrevocably constitute the Secretary of the Company as attorney-in-fact, with
full power of substitution, to transfer said stock on the books of the Company.

Dated: ________________________, 20____

                                                    ____________________________
                                                    (Signature)

                                                    ____________________________
                                                    (Print Name)

THIS STOCK POWER MAY ONLY BE UTILIZED IN CONNECTION WITH THE PROVISIONS OF THE
SECURITY AGREEMENT DATED AS OF ____________, 200__, BY AND BETWEEN THE SIGNATORY
HERETO AND THE COMPANY.

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