EXHIBIT 4.1

                         COMMON STOCK PURCHASE AGREEMENT

         THIS COMMON STOCK PURCHASE AGREEMENT (the "Agreement") is made and
entered into as of March 19, 2008 (the "Effective Date") by and between Geron
Corporation, a Delaware corporation having its principal place of business at
230 Constitution Drive, Menlo Park, California 94025 (the "Company"), and David
D. Bohannon Organization, a California corporation having an office at 60
Hillsdale Mall, San Mateo, CA 94403-3497 (the "Acquirer").

     A.   The  Company  has  agreed to issue,  and the  Acquirer  has  agreed to
          accept,  shares of the  Company's  common  stock,  par value $.001 per
          share (the  "Common  Stock") to Acquirer  in payment of the  Company's
          base rent  obligations for the period from August 1, 2008 through July
          31, 2012 under a lease dated  January 20, 1993 to the  premises at 200
          Constitution Drive, Menlo Park,  California,  as amended and extended,
          and a lease dated March 25, 1996 to the  premises at 230  Constitution
          Drive, Menlo Park, California,  as amended and extended (collectively,
          the "Leases").

     B.   The  Acquirer  and  the  Company  desire  to  specify  the  terms  and
          conditions of the Company's issuance of such common stock.

THE PARTIES AGREE AS FOLLOWS:

1.     ISSUANCE OF SHARES; PURCHASE PRICE. The Acquirer hereby acquires and the
       Company hereby issues to Acquirer 742,158 shares (the "Shares") of Common
       Stock in consideration of the premises conveyed pursuant to the Leases.
       Upon issuance and delivery of the certificate(s) for the Shares, all
       Shares shall be duly authorized and validly issued and represent fully
       paid shares of the Company's Common Stock.

2.       CLOSING; DELIVERY

     2.1  The consummation of the transaction  contemplated by this Agreement (a
          "Closing")  shall be held at such time and place as is mutually agreed
          upon  between  the  parties,  but in any event no later  than five (5)
          business days after the Effective Date of this Agreement (the "Closing
          Date"). At the Closing,  the Company shall deliver to the Acquirer one
          or more  certificates  representing  all of the Shares,  which  Shares
          shall be issued in the name of the  Acquirer  or its  designee  and in
          such denominations as the Acquirer shall specify.

     2.2  The   Company's   obligations   to  issue   and   deliver   the  stock
          certificate(s)  representing the Shares to the Acquirer at the Closing
          shall be subject to the following  conditions,  which may be waived by
          the Company:

                  2.2.1    the covenants and obligations that the Acquirer is
                           required to perform or to comply with pursuant to
                           this Agreement, at or prior to the Closing, must have
                           been duly performed and complied with in all material
                           respects; and

                  2.2.2    the representations and warranties made by the
                           Acquirer herein shall be true and correct in all
                           material respects as of the Closing Date.

     2.3  The   Acquirer's   obligation   to  accept   delivery   of  the  stock
          certificate(s) representing the Shares at the Closing shall be subject
          to the following conditions, any one or more of which may be waived by
          the Acquirer:

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                  2.3.1    the covenants and obligations that the Company is
                           required to perform or to comply with pursuant to
                           this Agreement, at or prior to the Closing, must have
                           been duly performed and complied with in all material
                           respects;

                  2.3.2    The Company shall have available under its
                           Certificate of Incorporation sufficient authorized
                           shares of Common Stock to issue the Shares to the
                           Acquirer; and

                  2.3.3    the representation and warranties made by the Company
                           herein shall be true and correct in all material
                           respects as of any Closing Date.

3. RESTRICTIONS ON RESALE OF SHARES.

     3.1  Legends. The Acquirer understands and acknowledges that the Shares are
          not  registered  under the Securities Act of 1933 (the "Act") and that
          under the Act and other  applicable  laws the Acquirer may be required
          to hold such  Shares  for an  indefinite  period of time.  Each  stock
          certificate representing Shares shall bear the following legends:

          "THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER  THE
          SECURITIES  ACT OF 1933, AS AMENDED (THE "ACT").  ANY TRANSFER OF SUCH
          SECURITIES SHALL BE INVALID UNLESS A REGISTRATION  STATEMENT UNDER THE
          ACT IS IN EFFECT AS TO SUCH  TRANSFER  OR, IN THE  OPINION  OF COUNSEL
          REASONABLY ACCEPTABLE TO THE COMPANY, SUCH REGISTRATION IS UNNECESSARY
          FOR SUCH TRANSFER TO COMPLY WITH THE ACT. THE  SECURITIES  REPRESENTED
          HEREBY  ARE  SUBJECT  TO  THE  TERMS  OF  THE  COMMON  STOCK  PURCHASE
          AGREEMENT,  DATED AS OF MARCH 19, 2008. A COPY OF THE AGREEMENT CAN BE
          OBTAINED FROM THE SECRETARY OF THE COMPANY."

     3.2  Limits on Sales. The Acquirer agrees that if it decides to resell some
          or all of the  Shares,  it will do so  only in an  appropriate  manner
          through orderly sales executed through a top-tier  brokerage firm, and
          based upon whether the shares are registered or unregistered, i.e., on
          the Nasdaq  National  Market or in a Rule 144A compliant  transaction.
          Subject to the foregoing restrictions, the Acquirer may sell or resell
          the Shares in any lot size, or at any volume, desired by the Acquirer.

     3.3  Further Limitations. The Company shall not be required (i) to transfer
          on its books any Shares that have been sold or  otherwise  transferred
          in violation of any of the  provisions of this Agreement or applicable
          securities laws; or (ii) to treat as owner of such Shares or to accord
          the  right  to  vote  or pay  dividends  to  any  purchaser  or  other
          transferee  to whom such  Shares  shall  have been so  transferred  in
          violation of any of the  provisions  of this  Agreement or  applicable
          securities laws.

4. REGISTRATION RIGHTS.

     4.1  The Company agrees to file with the Securities and Exchange Commission
          (the  "Commission"),  as promptly as  practicable  using  commercially
          reasonable  efforts  and in any event  within one  hundred  and twenty
          (120) days after the Closing Date, a registration  statement under the
          Act (the "Registration  Statement"),  on Form S-3 or other appropriate
          form, so as to permit a non-underwritten public offering and resale of
          the  Shares  under  the Act by the  Acquirer.  The  Company  agrees to
          diligently pursue making that Registration  Statement  effective.  The
          Company  will make  commercially  reasonable  efforts  to  notify  the
          Acquirer of the effectiveness of the Registration Statement within one
          (1) business day of receiving notice from the Commission declaring the
          Registration  Statement  effective,  but no later  than  the  close of
          business  (Pacific  Time) of the second  business day after receipt of
          such notice from the Commission.

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     4.2  The Company  shall  notify the Acquirer as promptly as possible of any
          review   initiated  by  the  Commission   with  respect  to  any  such
          Registration Statement.

     4.3  The  Company  will   maintain  the   Registration   Statement  or  any
          post-effective  amendment thereto filed under this Section 4 effective
          under  the Act  until  the  earliest  of (i) the date that none of the
          Shares  covered  by  such   Registration   Statement  are  issued  and
          outstanding,  (ii) the date  that all of the  Shares  have  been  sold
          pursuant to such Registration  Statement,  (iii) the date the Acquirer
          receives an opinion of counsel to the Company,  which counsel shall be
          reasonably  acceptable  to the  Acquirer,  that the Shares may be sold
          under the  provisions  of Rule 144, (iv) the date that all Shares have
          been  otherwise  transferred  to  persons  who may trade  such  shares
          without restriction under the Act, and the Company has delivered a new
          certificate  or other  evidence of ownership for such  securities  not
          bearing a restrictive  legend,  or (v) the date all Shares may be sold
          at any time  pursuant  to Rule 144 or any  similar  provision  then in
          effect under the Act in the opinion of counsel to the  Company,  which
          counsel   shall  be   reasonably   acceptable  to  the  Acquirer  (the
          "Effectiveness Period").

     4.4  All fees,  disbursements and out-of-pocket expenses and costs incurred
          by the Company in connection  with the  preparation  and filing of the
          Registration  Statement  under  Section  4.1  and  in  complying  with
          applicable   securities   and  Blue  Sky  laws   (including,   without
          limitation,  all attorneys' fees of the Company) shall be borne by the
          Company.  The  Acquirer  shall  bear the cost of  underwriting  and/or
          brokerage discounts,  fees and commissions,  if any, applicable to the
          Shares being registered and the fees and expenses of their counsel.

     4.5  The Company,  at its expense,  shall furnish the Acquirer with respect
          to  the  Shares  registered  under  the  Registration  Statement  such
          reasonable   number   of  copies   of  the   Registration   Statement,
          prospectuses  and  preliminary  prospectuses  in  conformity  with the
          requirements  of the Act and such other  documents as the Acquirer may
          reasonably  request,  in order to facilitate  the public sale or other
          disposition  of all or any of the  Shares by the  Acquirer,  provided,
          however,  that the  obligation  of the  Company to  deliver  copies of
          prospectuses  or  preliminary  prospectuses  to the Acquirer  shall be
          subject to the receipt by the Company of  reasonable  assurances  from
          the  Acquirer  that the  Acquirer  will  comply  with  the  applicable
          provisions of the Act and of such other securities or blue sky laws as
          may be applicable in connection  with any use of such  prospectuses or
          preliminary prospectuses.

     4.6  The  Acquirer  will  cooperate  with the  Company in all  respects  in
          connection  with  this  Agreement,   including  timely  supplying  all
          information  reasonably  requested by the Company (which shall include
          all information  regarding the Acquirer and proposed manner of sale of
          the Shares required to be disclosed in any Registration Statement) and
          executing  and  returning  all  documents   reasonably   requested  in
          connection with the  registration  and sale of the Shares and entering
          into  and  performing   their   obligations   under  any  underwriting
          agreement,  if the offering is an underwritten  offering, in usual and
          customary form, with the managing  underwriter or underwriters of such
          underwritten  offering.  Nothing in this Agreement  shall obligate the
          Acquirer to consent to be named as an underwriter in any  Registration
          Statement.

5. REPRESENTATIONS AND ACKNOWLEDGEMENT OF THE COMPANY.

         The Company hereby represents, warrants and covenants to the Acquirer
         as follow:

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     5.1  Organization,  Good  Standing  and  Qualification.  The  Company  is a
          corporation  duly  organized,  validly  existing and in good  standing
          under  the  laws of the  State  of  Delaware  and  has  all  requisite
          corporate  power  and  authority  to  carry  on  its  business  as now
          conducted and as presently  proposed to be  conducted.  The Company is
          duly  qualified  to  transact  business  and is in good  standing as a
          foreign  corporation in each  jurisdiction  in which the failure to so
          qualify  would  have a  material  adverse  effect on its  business  or
          properties.

     5.2  Authorization.  The  Company  has full  right,  power,  authority  and
          capacity  to  enter  into  this   Agreement  and  to  consummate   the
          transactions  contemplated hereby,  including the requirements for the
          use of Form S-3 for  registration  of the  Shares  and has  taken  all
          necessary action to authorize the execution,  delivery and performance
          of this  Agreement.  Upon execution and delivery,  this Agreement will
          constitute a valid and binding  obligation of the Company  enforceable
          against  the  Company in  accordance  with its  terms,  except as such
          enforceability  may be limited by applicable  bankruptcy,  insolvency,
          reorganization,   moratorium,   fraudulent  transfer,  liquidation  or
          similar laws relating to, or affecting  generally,  the enforcement of
          creditor's  rights and remedies or by other  equitable  principles  of
          general application from time to time in effect.

     5.3  Valid  Issuance of Common  Stock.  The Shares,  when issued,  sold and
          delivered in  accordance  with the terms hereof for the  consideration
          expressed  herein,  will be duly and  validly  authorized  and issued,
          fully paid and  nonassessable  and free of  restrictions  on  transfer
          other  than   restrictions   on  transfer  under  this  Agreement  and
          applicable state and federal securities laws.

     5.4  Legal Proceedings and Orders. There is no action, suit,  proceeding or
          investigation pending or threatened against the Company that questions
          the  validity of this  Agreement  or the right of the Company to enter
          into this  Agreement or to consummate  the  transactions  contemplated
          hereby, nor is the Company aware of any basis for any of the forgoing.
          The  Company is neither a party nor subject to the  provisions  of any
          order, writ, injunction, judgment or decree of any court or government
          agency or instrumentality that would affect the ability of the Company
          to  enter  into  this  Agreement  or to  consummate  the  transactions
          contemplated hereby.

6. REPRESENTATIONS AND ACKNOWLEDGMENTS OF THE ACQUIRER.

     The Acquirer hereby represents, warrants, acknowledges and agrees that:

     6.1  Investment.  The Acquirer is acquiring  the Shares for the  Acquirer's
          own  account,  and not directly or  indirectly  for the account of any
          other person.  The Acquirer is acquiring the Shares for investment and
          not  with  a  view  to  distribution  or  resale  thereof,  except  in
          compliance  with  the Act  and any  applicable  state  law  regulating
          securities.

     6.2  Access to  Information.  Acquirer has consulted with its own attorney,
          accountant, or investment advisor as the Acquirer has deemed advisable
          with respect to the investment and has determined its  suitability for
          Acquirer.  The Acquirer has had the  opportunity  to ask questions of,
          and to receive  answers from,  appropriate  executive  officers of the
          Company with respect to the terms and  conditions of the  transactions
          contemplated  hereby  and  with  respect  to  the  business,  affairs,
          financial  condition  and results of  operations  of the Company.  The
          Acquirer has had access to such financial and other  information as is
          necessary in order for the Acquirer to make a fully informed  decision
          as to investment in the Company, and has had the opportunity to obtain
          any additional information necessary to verify any of such information
          to which the  Acquirer  has had  access.  Acquirer  acknowledges  that
          neither  the Company nor any of its  officers,  directors,  employees,
          agents,  representatives,  or advisors have made any representation or
          warranty other than those specifically expressed herein.

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     6.3  Business and Financial Expertise.  The Acquirer further represents and
          warrants  that it has such  business or  financial  expertise as to be
          able to evaluate  its  investment  in the Company and  purchase of the
          Shares.

     6.4  Speculative Investment.  The Acquirer acknowledges that the investment
          in the  Company  represented  by the Shares is highly  speculative  in
          nature and is subject to a high  degree of risk of loss in whole or in
          part;  the amount of such  investment  is within the  Acquirer's  risk
          capital means and is not so great in relation to the Acquirer's  total
          financial  resources as would jeopardize the personal  financial needs
          of the Acquirer in the event such  investment were lost in whole or in
          part.

     6.5  Unregistered Securities. Acquirer acknowledges that:

                  6.5.1    The Acquirer must bear the economic risk of
                           investment  for an indefinite  period of time because
                           the Shares have  not  been  registered  under  the
                           Act and  therefore  cannot  and  will  not be sold
                           unless  they are subsequently  registered under the
                           Act or an exemption from such registration is
                           available.  The Company has made no  agreements,
                           covenants  or  undertakings  whatsoever  to register
                           any of the Shares under the Act, except as provided
                           in Section 4 above.  The Company has made no
                           representations,  warranties  or  covenants
                           whatsoever  as to whether any  exemption  from the
                           Act,  including,  without  limitation,  any exemption
                           for limited sales in routine  brokers'  transactions
                           pursuant to Rule 144 under the Act, will become
                           available and any such  exemption  pursuant to Rule
                           144, if available  at all,  will not be  available
                           unless:  (i) a public  trading  market then exists in
                           the Company's  common  stock,  (ii) the Company has
                           complied with the information  requirements  of Rule
                           144,  and (iii) all  other  terms and  conditions  of
                           Rule 144 have been satisfied.

                  6.5.2     Transfer of the Shares has not been registered or
                            qualified under any applicable state law regulating
                            securities and, therefore, the Shares cannot and
                            will not be sold unless they are subsequently
                            registered or qualified under any such act or an
                            exemption therefrom is available. The Company has
                            made no agreements, covenants or undertakings
                            whatsoever to register or qualify any of the Shares
                            under any such act. The Company has made no
                            representations, warranties or covenants whatsoever
                            as to whether any exemption from any such act will
                            become available.

                  6.5.3     The  Acquirer  hereby  certifies  that it is an
                            "accredited  investor" as that term is defined in
                            Rule 501 under the Act.

     6.6  Authorization.  The  Acquirer  has full right,  power,  authority  and
          capacity  to  enter  into  this   Agreement  and  to  consummate   the
          transactions  contemplated  hereby  and  thereby  and  has  taken  all
          necessary action to authorize the execution,  delivery and performance
          of this  Agreement.  Upon execution and delivery,  this Agreement will
          constitute a valid and binding obligation of the Acquirer  enforceable
          against the  Acquirer  in  accordance  with its terms,  except as such
          enforceability  may be limited by applicable  bankruptcy,  insolvency,
          reorganization,   moratorium,   fraudulent  transfer,  liquidation  or
          similar laws relating to, or affecting  generally,  the enforcement of
          creditor's  rights and remedies or by other  equitable  principles  of
          general application from time to time in effect.

7.       TAX ADVICE. The Acquirer acknowledges that the Acquirer has not relied
         and will not rely upon the Company or the Company's counsel with
         respect to any tax consequences related to the ownership, purchase, or
         disposition of the shares. The Acquirer assumes full responsibility for
         all such consequences and for the preparation and filing of all tax
         returns and elections which may or must be filed in connection with the
         shares.

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8.       NOTICES. Any notice or other communication required or permitted
         hereunder shall be in writing and shall be deemed to have been duly
         given on the date of delivery if delivered personally or by facsimile,
         or one day, not including Saturdays, Sundays, or national holidays,
         after sending if sent by national overnight delivery service, or five
         days, not including Saturdays, Sundays, or national holidays, after
         mailing if mailed by first class United States mail, certified or
         registered with return receipt requested, postage prepaid, and
         addressed as follows:

                  To the Company at:        Geron Corporation
                                            230 Constitution Drive
                                            Menlo Park, California  94025
                                            Attention: Chief Financial Officer
                                            Telephone:        (650) 473-7700
                                            Facsimile:        (650) 473-7750



                  With a copy to:   Geron Corporation
                                            230 Constitution Drive
                                            Menlo Park, California  94025
                                            Attention: Senior Director, Legal
                                            Telephone:        (650) 473-7775
                                            Facsimile:        (650) 566-7181



                  To the Acquirer at:       David D. Bohannon Organization
                                            60 Hillsdale Mall
                                            San Mateo, CA 94403-3497
                                            Attention: Chief Financial Officer
                                            Telephone:        (650) 345-8222
                                            Facsimile:        (650) 573-5457


9.      BINDING EFFECT. This Agreement shall be binding upon the heirs, legal
        representatives and successors of the Company and of the Acquirer;
        provided, however, that the Acquirer may not assign any rights or
        obligations under this Agreement. The Company's rights under this
        Agreement shall be freely assignable.

10.     ATTORNEYS' FEES. If any action or proceeding or arbitration is commenced
        by either party to enforce its rights under this Agreement or to collect
        damages as a result of the breach of any of the provisions of this
        Agreement, the prevailing party in such action or proceeding or
        arbitration, including any bankruptcy, insolvency or appellate
        proceedings, shall be entitled to recover all reasonable out-of-pocket
        costs and expenses, including, without limitation, reasonable attorneys'
        fees and court costs, in addition to any other relief awarded by the
        court or arbitrator.

11.     GOVERNING LAW. This Agreement shall be governed by and construed in
        accordance with the laws of the State of California, United States of
        America.

12.     INVALID PROVISIONS. In the event that any provision of this Agreement is
        found to be invalid or otherwise unenforceable by a court or other
        tribunal of competent jurisdiction, such invalidity or unenforceability
        shall not be construed as rendering any other provision contained herein
        invalid or unenforceable, and all such other provisions shall be given
        full force and effect to the same extent as though the invalid and
        unenforceable provision was not contained herein.

13.     COUNTERPARTS. This Agreement may be executed in any number of identical
        counterparts, each of which shall be deemed an original, but all of
        which together shall constitute one and the same instrument.

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14.     AMENDMENTS. This Agreement or any provision hereof may be changed,
        waived, or terminated only by a statement in writing signed by the party
        against whom such change, waiver or termination is sought to be
        enforced.

15.     FUTURE COOPERATION. Each of the parties hereto agrees to cooperate at
        all times from and after the date hereof with respect to all of the
        matters described herein, and to execute such further assignments,
        releases, assumptions, amendments of the Agreement, notifications and
        other documents as may be reasonably requested for the purpose of giving
        effect to, or evidencing or giving notice of, the transactions
        contemplated by this Agreement.

16.     ENTIRE AGREEMENT. This Agreement, and the Leases, constitute the entire
        agreement of the parties pertaining to the Shares and supersede all
        prior and contemporaneous agreements, representations, and
        understandings of the parties with respect thereto.

    IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the Effective Date.

                                     Geron Corporation


                                      /s/ David L. Greenwood
                                     ---------------------------
                                     By:      David L. Greenwood
                                     Title:   Executive Vice President and Chief
                                              Financial Officer

                                     DAVID D. BOHANNON ORGANIZATION


                                      /s/ Scott Bohannon
                                     ---------------------------
                                     By:      Scott Bohannon
                                     Title:   Senior Vice President


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