EXHIBIT 4.1


                         COMMON STOCK PURCHASE AGREEMENT

THIS COMMON STOCK PURCHASE  AGREEMENT  ("Agreement") is made and entered into as
of May 29, 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 ("Geron"),  and Samchully Pharm. Co., Ltd.,
having a principal place of business at 947-7, Daechi-dong,  Gangnam-gu,  Seoul,
Korea ("Manufacturer").

     A.   Geron  and  Manufacturer  are  the  parties  to  that  certain  Master
          Manufacturing  Agreement dated as of March 9, 2005 (the "Manufacturing
          Agreement"),  and related Addendum Agreements  ("Addendum  Agreement")
          under which Geron has agreed to purchase certain products and services
          from  Manufacturer and Manufacturer has agreed to supply such products
          and services to Geron on the terms set forth therein.

     B.   Pursuant to the Amendment No. 1 to the Manufacturing Agreement,  dated
          as of May 12,  2008,  Geron is entitled to pay the  purchase  price of
          products  and  services by delivery of shares of Geron's  Common Stock
          (the "Shares").

THE PARTIES AGREE AS FOLLOWS:

1.   ISSUANCE OF SHARES; ADJUSTMENTS

     As payment of the First Installment specified in Amendment No. 1 to
Addendum Agreement No. 8, Geron will issue and deliver certificates for 251,637
Shares. 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 Geron'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  Geron  shall  make
          commercially  reasonable  efforts to  accomplish  the Closing no later
          than five (5)  business  days after the  Effective  Date  hereof  (the
          "Closing Date").  At the Closing,  Geron shall deliver to Manufacturer
          one or more certificates  representing all of the Shares, which Shares
          shall be issued in the name of  Manufacturer  or its  designee  and in
          such denominations as Manufacturer shall specify.

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

          2.2.1     the covenants and obligations that  Manufacturer 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  Manufacturer
                    herein shall be true and correct in all material respects as
                    of the Closing Date.

     2.3  Manufacturer'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
          Manufacturer:

          2.3.1     the  covenants  and  obligations  that Geron 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;
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          2.3.2     Geron  shall  have  available   under  its   Certificate  of
                    Incorporation  sufficient  authorized shares of Common Stock
                    to issue the Shares to Manufacturer; and

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

3.   RESTRICTIONS ON RESALE OF SHARES

     3.1  Legends. Manufacturer 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  Manufacturer 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 GERON,  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 BY AND BETWEEN GERON AND
               MANUFACTURER  DATED AS OF MAY 29, 2008.  A COPY OF THE  AGREEMENT
               CAN BE OBTAINED FROM THE SECRETARY OF GERON."

     3.2  Limits on Sales. Manufacturer agrees that if it decides to resell some
          or all of the  Shares,  it  will  do so  only  through  orderly  sales
          executed  through a top-tier  brokerage  house,  and in an appropriate
          manner based upon whether the shares are  registered or  unregistered,
          i.e.,  on  the  Nasdaq  Global  Market  or in a  Rule  144A  compliant
          transaction.  Manufacturer  further  agrees that it will not engage in
          short selling with respect to the Shares.

     3.3  Further  Limitations.  Geron 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  Geron agrees to make commercially  reasonable efforts to file with the
          Securities and Exchange Commission (the "Commission")  within ten (10)
          business 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  Manufacturer.  Geron agrees
          to diligently  pursue  making the  Registration  Statement  effective.
          Geron will make commercially reasonable efforts to notify Manufacturer
          of the  effectiveness  of the  Registration  Statement  within one (1)
          business day of receiving notice from the Commission.

     4.2  Geron will maintain the Registration  Statement and 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 Manufacturer receives an opinion of counsel
          from  Geron,   which  counsel   shall  be  reasonably   acceptable  to
          Manufacturer, that the Shares may be sold under the provisions of Rule
          144  without  limitation  as to volume,  (iv) the date that all Shares
          have been  otherwise  transferred to persons who may trade such shares
          without  restriction  under the Act,  and Geron  has  delivered  a new
          certificate or other evidence of ownership for such securities not

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          bearing a restrictive  legend,  or (v) the date all Shares may be sold
          at any time, without volume or manner of sale limitations  pursuant to
          Rule 144 or any similar  provision then in effect under the Act in the
          opinion  of  counsel  to  Geron,  which  counsel  shall be  reasonably
          acceptable to Manufacturer.

     4.3  Geron, at its expense,  shall furnish to Manufacturer  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 Manufacturer  may reasonably  request,
          in order to facilitate the public sale or other  disposition of all or
          any of  the  Shares  by  Manufacturer,  provided,  however,  that  the
          obligation of Geron to deliver copies of  prospectuses  or preliminary
          prospectuses to Manufacturer  shall be subject to the receipt by Geron
          of reasonable  assurances from  Manufacturer  that  Manufacturer  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.

     4.4  All fees,  disbursements and out-of-pocket expenses and costs incurred
          by  Geron  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 Geron)  shall be borne by Geron.
          Manufacturer   shall   bear  the  cost  of  fees   and   expenses   of
          Manufacturer's counsel.

     4.5  Geron will advise Manufacturer  promptly after it shall receive notice
          or  obtain  knowledge  of  the  issuance  of  any  stop  order  by the
          Commission   delaying  or   suspending   the   effectiveness   of  the
          Registration Statement or of the initiation of any proceeding for that
          purpose,  and Geron will use its  commercially  reasonable  efforts to
          prevent the issuance of any stop order or to obtain its  withdrawal at
          the earliest possible moment if such stop order should be issued.

     4.6  With a view to making  available to Manufacturer  the benefits of Rule
          144 (or its  successor  rule) and any other rule or  regulation of the
          Commission that may at the time permit Manufacturer to sell the Shares
          to the public without registration, Geron covenants and agrees to: (i)
          make  and keep  public  information  available,  as  those  terms  are
          understood  and  defined in Rule 144,  until the  earliest of (A) such
          date as all of the  Shares may be resold  pursuant  to Rule 144 or any
          other  rule of  similar  effect or (B) such date as all of the  Shares
          shall have been resold;  and (ii) file with the Commission in a timely
          manner all reports and other documents required of Geron under the Act
          and  under  the  Securities  Exchange  Act of 1934,  as  amended  (the
          "Exchange Act").

     4.7  Manufacturer  will  cooperate with Geron in all respects in connection
          with  this  Agreement,  including  timely  supplying  all  information
          reasonably  requested by Geron (which  shall  include all  information
          regarding  Manufacturer  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  Manufacturer  to
          consent to be named as an underwriter in any Registration Statement.

5.   INDEMNIFICATION

     5.1  Geron agrees to indemnify  and hold  harmless  Manufacturer  (and each
          person,  if any,  who  controls  Manufacturer  within  the  meaning of
          Section 15 of the Act, and each officer and director of  Manufacturer)
          against any and all losses, claims, damages or liabilities (or actions
          or  proceedings  in respect  thereof),  joint or several,  directly or
          indirectly  based upon or arising out of (i) any untrue  statement  or
          alleged  untrue  statement  of  any  material  fact  contained  in the
          Registration Statement, any preliminary prospectus, final prospectus

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          or summary prospectus contained therein or used in connection with the
          offering of the Shares,  or any  amendment or supplement  thereto,  or
          (ii)  any  omission  or  alleged  omission  to state a  material  fact
          required  to be stated  therein or  necessary  to make the  statements
          therein not misleading; and Geron will reimburse each such indemnified
          party for any legal or any other expenses  reasonably incurred by them
          in connection with investigating, preparing, pursuing or defending any
          such loss,  claim,  damage,  liability,  action or proceeding,  except
          insofar as any such loss, claim, damage, liability, action, proceeding
          or expense (A) arises out of or is based upon an untrue  statement  or
          alleged untrue  statement or omission or alleged  omission made in the
          Registration  Statement,   any  such  preliminary  prospectus,   final
          prospectus,  summary  prospectus,  amendment or supplement in reliance
          upon and in conformity with written information  furnished to Geron by
          Manufacturer or such other person expressly for use in the preparation
          thereof,  (B) the failure of Manufacturer to comply with its covenants
          and  agreements  contained  in Sections 7.1 or 7.5.2 hereof or (C) any
          misstatement  or omission in any  prospectus  that is corrected in any
          subsequent  prospectus that was delivered to Manufacturer prior to the
          pertinent sale or sales by  Manufacturer.  Such indemnity shall remain
          in full force and effect, regardless of any investigation made by such
          indemnified  party and shall  survive  the  transfer  of the Shares by
          Manufacturer.

     5.2  Manufacturer  agrees to indemnify  and hold  harmless  Geron (and each
          person, if any, who controls Geron within the meaning of Section 15 of
          the Act,  each officer of Geron who signs the  Registration  Statement
          and each director of Geron) from and against losses,  claims,  damages
          or liabilities (or actions or proceedings in respect  thereof),  joint
          or several,  directly or indirectly  based upon or arising out of, (i)
          any  failure  of   Manufacturer  to  comply  with  the  covenants  and
          agreements  contained  in  Sections  7.1 and 7.5.2  hereof or (ii) any
          untrue  statement of a material  fact  contained  in the  Registration
          Statement or any omission of a material  fact required to be stated in
          the  Registration   Statement  or  necessary  in  order  to  make  the
          statements in the Registration Statement not misleading if such untrue
          statement or omission was made in reliance upon and in conformity with
          written information furnished to Geron by or on behalf of Manufacturer
          specifically  for use in  preparation of the  Registration  Statement;
          provided,  however,  that Manufacturer shall not be liable in any such
          case for (A) any untrue  statement  or  omission  in the  Registration
          Statement,  prospectus,  or other such  document  which  statement  is
          corrected  by  Manufacturer  and  delivered to Geron prior to the sale
          from which such loss occurred, (B) any untrue statement or omission in
          any prospectus  which is corrected by  Manufacturer  in any subsequent
          prospectus, or supplement or amendment thereto, and delivered to Geron
          prior to the sale or sales from which a loss or  liability  arose,  or
          (C) any  failure  by Geron to  fulfill  any of its  obligations  under
          Section 5.1 hereof.

     5.3  Promptly  after  receipt  by any  indemnified  person of a notice of a
          claim or the beginning of any action in respect of which  indemnity is
          to be sought against an  indemnifying  person pursuant to this Section
          5, such  indemnified  person shall notify the  indemnifying  person in
          writing of such claim or of the  commencement of such action,  but the
          omission to so notify the indemnifying  party will not relieve it from
          any liability  which it may have to any  indemnified  party under this
          Section 5 (except  to the extent  that such  omission  materially  and
          adversely  affects  the  indemnifying  party's  ability to defend such
          action) or from any  liability  otherwise  than under this  Section 5.
          Subject to the provisions  hereinafter stated, in case any such action
          shall be  brought  against an  indemnified  person,  the  indemnifying
          person shall be entitled to  participate  therein,  and, to the extent
          that it shall elect by written  notice  delivered  to the  indemnified
          party  promptly  after  receiving  the  aforesaid   notice  from  such
          indemnified  party,  shall be entitled to assume the defense  thereof,
          with counsel reasonably satisfactory to such indemnified person. After
          notice from the indemnifying  person to such indemnified person of its
          election to assume the defense thereof, such indemnifying person shall
          not be  liable  to  such  indemnified  person  for any  legal  expense
          subsequently  incurred by such  indemnified  person in connection with
          the defense thereof, provided,  however, that if there exists or shall
          exist a conflict of  interest  that would make  inappropriate,  in the
          reasonable opinion of counsel to the indemnified  person, for the same
          counsel to represent both the indemnified person and such indemnifying
          person or any affiliate  or  associate  thereof,  the  indemnified

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          person  shall be  entitled to retain its own counsel at the expense of
          such  indemnifying  person;  provided,  however,  that no indemnifying
          person shall be responsible for the fees and expenses of more than one
          separate  counsel  (together with  appropriate  local counsel) for all
          indemnified  parties.  In no event  shall any  indemnifying  person be
          liable in  respect to any  amounts  paid in  settlement  of any action
          unless the  indemnifying  person shall have approved the terms of such
          settlement.  No indemnifying  person shall,  without the prior written
          consent  of the  indemnified  person,  effect  any  settlement  of any
          pending or threatened  proceeding in respect of which any  indemnified
          person is or could  have been a party and  indemnification  could have
          been  sought  hereunder  by  such  indemnified  person,   unless  such
          settlement  includes  an  unconditional  release  of such  indemnified
          person from all  liability  on claims  that are the subject  matter of
          such proceeding.

     5.4  The provisions of this Section 5 shall survive the termination of this
          Agreement.

6.   REPRESENTATIONS AND ACKNOWLEDGEMENT OF GERON

     Geron hereby represents, warrants and covenants to Manufacturer as follows:

     6.1  Organization, Good Standing and Qualification.  Geron 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. Geron 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.

     6.2  Authorization.  All  corporate  action  on  the  part  of  Geron,  its
          officers,  directors and stockholders necessary for the authorization,
          execution  and  delivery of this  Agreement,  the  performance  of all
          obligations  of Geron  hereunder and the  authorization,  issuance and
          delivery  of the Shares  has been taken or will be taken  prior to the
          Closing,  and  this  Agreement,   when  executed  and  delivered  will
          constitute valid and legally binding obligations of Geron, enforceable
          against  Geron in  accordance  with their terms,  except as limited by
          applicable   bankruptcy,   insolvency,   reorganization,   moratorium,
          fraudulent  conveyance and other laws of general application affecting
          enforcement  of  creditors'  rights  generally,  as  limited  by  laws
          relating  to the  availability  of  specific  performance,  injunctive
          relief or other equitable remedies.

     6.3  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.

     6.4  Legal Proceedings and Orders. There is no action, suit,  proceeding or
          investigation  pending or threatened  against Geron that questions the
          validity  of this  Agreement  or the right of Geron to enter into this
          Agreement or to consummate the transactions  contemplated  hereby, nor
          is Geron aware of any basis for any of the forgoing.  Geron 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 Geron to enter into
          this Agreement or to consummate the transactions contemplated hereby.


7.   REPRESENTATIONS AND ACKNOWLEDGEMENTS OF MANUFACTURER

     Manufacturer hereby represents, warrants, acknowledges and agrees that:

     7.1  Investment.  Manufacturer  is acquiring the Shares for  Manufacturer's
          own  account,  and not directly or  indirectly  for the account of any
          other person. Manufacturer is acquiring the Shares for  investment and

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          not  with  a  view  to  distribution  or  resale  thereof,  except  in
          compliance  with  the Act  and any  applicable  state  law  regulating
          securities.

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

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

     7.4  Speculative Investment.  Manufacturer acknowledges that the investment
          in Geron 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  Manufacturer's risk capital means
          and is not so great in  relation  to  Manufacturer's  total  financial
          resources  as  would  jeopardize  the  personal   financial  needs  of
          Manufacturer  in the event  such  investment  were lost in whole or in
          part.

     7.5  Unregistered Securities. Manufacturer acknowledges that:

          7.5.1     Manufacturer  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.
                    Geron  has made no  agreements,  covenants  or  undertakings
                    whatsoever  to  register  any of the  Shares  under the Act,
                    except as  provided  in  Section 4 above.  Geron 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 Geron's  common
                    stock,   (ii)  Geron  has  complied  with  the   information
                    requirements  of Rule 144,  and  (iii)  all other  terms and
                    conditions of Rule 144 have been satisfied.

          7.5.2     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.  Geron has made
                    no  agreements,  covenants  or  undertakings  whatsoever  to
                    register  or qualify  any of the Shares  under any such act.
                    Geron has made no  representations,  warranties or covenants
                    whatsoever  as to whether  any  exemption  from any such act
                    will become available.

          7.5.3     Manufacturer  hereby  certifies  that  it is an  "Accredited
                    Investor" as that term is defined in Rule 501 under the Act.

     7.6  Authorization.  Manufacturer  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

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          of this  Agreement.  Upon execution and delivery,  this Agreement will
          constitute a valid and binding obligation of Manufacturer  enforceable
          against  Manufacturer  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.

8.   TAX ADVICE.  Manufacturer acknowledges that Manufacturer has not relied and
     will not rely  upon  Geron  or  Geron's  counsel  with  respect  to any tax
     consequences  related to the  ownership,  purchase,  or  disposition of the
     Shares.  Manufacturer 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.

9.   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 Geron at:                 Geron Corporation
                                       230 Constitution Drive
                                       Menlo Park, California  94025
                                       Attention: General Counsel
                                       Telephone:        (650) 473-7700
                                       Facsimile:        (650) 473-7750

          To Manufacturer at:          Kris S. Choi
                                       General Manager,
                                       Marketing and Business Development
                                       8F Samtan Bldg.
                                       Samchully Pharm. Co., Ltd.
                                       947-7, Daechi-dong Gangnam-gu
                                       Seoul, Korea  135-735
                                       e-mail:  choicsw@samchullypharm.com
                                       Telephone: +82 (0)2-527-6329
                                       Facsimile: +82 (0)2-561-6006

10.  BINDING  EFFECT.  This  Agreement  shall be binding  upon the heirs,  legal
     representatives  and  successors  of Geron and of  Manufacturer;  provided,
     however,  that  Manufacturer may not assign any rights or obligations under
     this Agreement.

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

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.

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.

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<PAGE>

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 Manufacturing Agreement, including
     all  Addenda  thereto,  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 Common Stock
Purchase Agreement as of the date first above written.


                                Geron Corporation

                                /s/ Thomas B. Okarma
                                --------------------------------------------
                                By:      Thomas B. Okarma
                                Title:   President and Chief Executive Officer


                                Samchully Pharm. Co., Ltd.

                                /s/ Tae-Sung Kim
                                --------------------------------------------
                                By:      Tae-Sung Kim
                                Title:   President and Chief Executive Officer

                                       8