Document:

EXHIBIT 4.2

                         COMMON STOCK PURCHASE AGREEMENT

         THIS COMMON STOCK PURCHASE AGREEMENT ("Agreement") is made and entered
into as of March 18, 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 Lonza
Walkersville, Inc., a Delaware corporation having its principal place of
business at 8830 Biggs Ford Road, Walkersville, Maryland 21793 ("Lonza").
Capitalized terms not otherwise defined herein shall have the meaning set forth
in the MSA and Project Order No. 1.

     A.   Geron and Cambrex Bio Science Walkersville, Inc. ("CBSW") entered that
          certain Master Services Agreement,  dated as of September 1, 2005 (the
          "MSA"),  pursuant to which CBSW agreed to perform certain  services on
          behalf of Geron  related to the  manufacture  of a product  containing
          human cells  intended for  therapeutic  use in humans on the terms set
          forth therein.

     B.   Geron  and  CBSW  entered  into  Project  Order  No. 1 to the MSA (the
          "Project Order No. 1") effective  September 1, 2005, pursuant to which
          Geron  is  entitled,   subject  to  certain  conditions,  to  pay  any
          compensation  owed to CBSW for Services  performed under Project Order
          No. 1 either in cash or in Geron's common stock (the "Common Stock").

     C.   Subject to the terms and conditions of the Second Amendment to Project
          Order No.1,  dated as of March 1, 2006  ("Amendment No. 2"), Geron and
          CBSW  agreed  that Geron  shall,  subject to  certain  conditions,  be
          entitled to pay up to  US$4,500,000  for Services  under Project Order
          No. 1 by delivery of Shares.

     D.   Effective  February 6, 2007,  Lonza completed its acquisition of CBSW,
          and  assumed  all  rights  and  obligations  of CBSW under the MSA and
          Project Order No. 1, as amended.

     E.   Subject to the terms and conditions of the Sixth  Amendment to Project
          Order No.1,  dated as of November 9, 2007, Geron and Lonza have agreed
          that Geron shall, subject to certain conditions, be entitled to pay an
          additional  US$4,000,000  for Services  under  Project  Order No. 1 by
          delivery  of  Shares,  for an  aggregate  total of up to  US$8,500,000
          payable in Stock.

THE PARTIES AGREE AS FOLLOWS:

   1. ISSUANCE OF SHARES; ADJUSTMENTS.

         1.1      As payment of the sixth Installment Payment specified in
                  Project Order No. 1, Geron will issue and deliver certificates
                  for 232,558 shares of Common Stock (the "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 no later than five (5) business days after the Effective
                  Date of this Agreement (the "Closing Date"). At the Closing,
                  Geron shall deliver to Lonza one or more certificates
                  representing all of the Shares, which Shares shall be issued
                  in the name of Lonza or its designee and in such denominations
                  as Lonza shall specify.

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

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

         2.3      Lonza'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 Lonza:

                  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;

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

                  2.3.3    the representations 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. Lonza 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 Lonza
                  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 LONZA, DATED MARCH 18, 2008. A COPY OF
                  THE AGREEMENT CAN BE OBTAINED FROM THE SECRETARY OF GERON."

         3.2      Limits on Sales. Lonza 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.

         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.

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   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 Lonza. Geron agrees to diligently
                  pursue making the Registration Statement effective. Geron will
                  make commercially reasonable efforts to notify Lonza 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.

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

         4.3      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 Lonza receives an opinion of counsel to Geron,
                  which counsel shall be reasonably acceptable to Lonza, that
                  the Shares may be sold under the provisions of Rule 144 or any
                  similar provision then in effect under the Act, or (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 bearing a
                  restrictive legend.

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

         4.5     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. Lonza shall bear the cost of all fees
                 and expenses of Lonza's counsel.

         4.6     Geron will advise Lonza 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 as promptly as possible if such stop
                 order should be issued.

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         4.7     With a view to making available to Lonza the benefits of Rule
                 144 (or its successor rule) and any other rule or regulation of
                 the Commission that may at the time permit Lonza 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(k) 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 Exchange Act of 1934, as amended.

         4.8      Lonza 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 Lonza 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 Lonza to
                  consent to be named as an underwriter in any Registration
                  Statement.

   5. INDEMNIFICATION.

         5.1      Geron agrees to indemnify and hold harmless Lonza (and each
                  person, if any, who controls Lonza within the meaning of
                  Section 15 of the Act, and each officer and director of Lonza)
                  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 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 arises out of or is
                  based upon (A) 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 or on behalf of Lonza expressly for use in the preparation
                  thereof, (B) the failure of Lonza 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
                  Lonza prior to the pertinent sale or sales by Lonza. 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 Lonza.

         5.2      Lonza agrees to indemnify and hold harmless Geron (and each
                  person, if any, who controls Geron within the meaning of
                  Section 15 of the Act, and each officer and 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 Lonza 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

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                  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 Lonza specifically for
                  use in preparation of the Registration Statement; provided,
                  however, that Lonza 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 Lonza 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 Lonza 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 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 a
                  party, 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 Lonza as follow:

         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.

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         6.2      Authorization. Geron 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 Geron enforceable against Geron 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.

         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 foregoing. 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 ACKNOWLEDGMENTS OF LONZA.

         Lonza hereby represents, warrants, acknowledges and agrees that:

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

         7.2      Access to Information. Lonza has consulted with its own
                  attorney, accountant, or investment advisor as Lonza has
                  deemed advisable with respect to the investment and has
                  determined its suitability for Lonza. Lonza 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. In connection with the
                  transactions contemplated hereunder, Geron may disclose to
                  Lonza information which may constitute material, non-public
                  information regarding Geron, and Lonza agrees to maintain in
                  confidence any such information; provided, however, such
                  information shall not include information (a) that is or
                  becomes part of the public domain, (b) that was in Lonza's
                  possession without any obligation of confidentiality prior to
                  the date Geron disclosed such information to Lonza, or (c)
                  that is supplied to Lonza by a third party which is not
                  subject to any restriction of confidentiality or
                  non-disclosure. Lonza has had access to such financial and
                  other information as is necessary in order for Lonza 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 Lonza has had
                  access. Lonza 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.

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         7.3      Business and Financial Expertise. Lonza 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. Lonza 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
                  Lonza's risk capital means and is not so great in relation to
                  Lonza's total financial resources as would jeopardize the
                  personal financial needs of Lonza in the event such investment
                  were lost in whole or in part.

         7.5      Unregistered Securities.  Lonza acknowledges that:

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

         7.6      Authorization. Lonza 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 Lonza enforceable against Lonza 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. Lonza acknowledges that Lonza 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. Lonza
         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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    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: 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 Lonza at:              Lonza Walkersville, Inc.
                                            8830 Biggs Ford Road
                                            Walkersville, Maryland 21793
                                            Attention:  Tim Harrigan
                                            Telephone:        (301) 898-7025
                                            Facsimile:        (301) 845-6099

                  With a copy to:           Lonza America Inc.
                                            25 Commerce Drive
                                            Allendale, New Jersey 07401
                                            Attention: Assistant General Counsel
                                            Telephone:        (201) 316-9422
                                            Facsimile:        (201) 378-5630

    10.  BINDING EFFECT. This Agreement shall be binding upon the heirs, legal
         representatives and successors of Geron and of Lonza.

    11.  GOVERNING LAW. This Agreement shall be governed by and construed in
         accordance with the laws of the State of Delaware, without giving
         effect to its conflicts of laws provisions.

    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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    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 MSA, and Project Order No. 1
         thereto as amended, 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.

                      REST OF PAGE INTENTIONALLY LEFT BLANK

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         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

                                     LonzaWalkersville, Inc.

                                       /s/ Shawn P. Cavanagh
                                     -------------------------------------------
                                     By:      Shawn P. Cavanagh
                                     Title:   President

                                     LonzaWalkersville, Inc.

                                       /s/ Timothy P. Harrigan
                                     -------------------------------------------
                                     By:      Timothy P. Harrigan
                                     Title:   Business Sector Controller

                                       10EXHIBIT 4.3

                         COMMON STOCK PURCHASE AGREEMENT

         THIS COMMON STOCK PURCHASE AGREEMENT ("Agreement") is made and entered
into as of March 21, 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 Girindus
America Inc., a Delaware corporation having its principal place of business at
8560 Reading Road, Cincinnati, Ohio, 45215 ("Manufacturer").

     A.   Geron  and  Manufacturer  are  the  parties  to  that  certain  Master
          Manufacturing   Agreement   dated  as  of   February   27,  2007  (the
          "Manufacturing  Agreement"),  and  related  Project  Orders  ("Project
          Order") under which Geron has agreed to purchase certain products from
          Manufacturer  and  Manufacturer  has agreed to supply such products to
          Geron on the terms set forth therein.

     B.   Pursuant to the  Manufacturing  Agreement,  Geron may pay the purchase
          price of  products  under any  Project  Order by delivery of shares of
          Geron's Common Stock (the "Shares").

THE PARTIES AGREE AS FOLLOWS:

    1. ISSUANCE OF SHARES; ADJUSTMENTS.

         1.1      As payment of the Third Installment under the Manufacturing
                  Agreement, Geron will issue and deliver certificates for
                  375,926 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 three (3) 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;

                                       1
<PAGE>

                  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 representations 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 MANUFACTURER AND GERON, DATED AS OF MARCH 21,
                  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 reputable brokerage house,
                  and in an appropriate manner based upon whether the shares are
                  registered or unregistered, i.e., on the Nasdaq National
                  Market or in a Rule 144A or Rule 144 compliant transaction.
                  Manufacturer further agrees that it will not itself engage in
                  short selling with respect to the Stock. Provided that the
                  brokerage house meets the requirements set forth herein,
                  nothing shall limit Manufacturer's right to select the
                  brokerage house of its choice.

         3.3      Removal of Legends. Any legend endorsed on a certificate
                  evidencing the Shares shall be removed, and Geron shall issue
                  a certificate without such legend to the Manufacturer, if such
                  Shares are being sold pursuant to an effective registration
                  statement under the Act or pursuant to Rule 144 promulgated
                  thereunder, and the purchaser of registered Shares may
                  immediately resell such Shares without restriction; provided,
                  however, that in the case of a sale pursuant to Rule 144, such
                  holder of Shares shall provide such information as is
                  reasonably requested by Geron to ensure that such Shares may
                  be sold in reliance on Rule 144.

    4. REGISTRATION RIGHTS

         4.1      Geron agrees to make commercially reasonable efforts to file
                  with the Securities and Exchange Commission (the
                  "Commission"), within five (5) 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 will
                  exercise reasonable efforts to cause the form of the
                  Registration Statement to satisfy all applicable requirements
                  of the Act and the regulations of the Commission thereunder.
                  Geron agrees to diligently pursue making the Registration
                  Statement effective. Geron will 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

                                       2
<PAGE>

                  from Geron, which counsel shall be reasonably acceptable to
                  Manufacturer, that the Shares may be sold under the provisions
                  of Rule 144 or any similar provision then in effect under the
                  Act, or (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 bearing a restrictive legend.

         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 (the "Exchange Act"), as amended.

         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.

         4.8      Geron shall prepare and file with the SEC such amendments and
                  supplements to the Registration Statement as may be necessary
                  to comply with the provisions of the Act with respect to the
                  disposition of all Shares covered by the Registration
                  Statement; provided, however, that promptly after filing a
                  registration statement or any amendments or supplements
                  thereto, or comparable statements under securities or blue sky
                  laws of any jurisdiction, Geron will furnish one (1) copy to
                  counsel designated by Manufacturer.

                                       3
<PAGE>

         Geron shall promptly notify Manufacturer, at any time when the
         prospectus included in or relating to the Registration Statement (the
         "Prospectus") is required to be delivered under the Act, of the
         happening of any event as a result of which the Prospectus contains an
         untrue statement of a material fact or omits any fact necessary to make
         the statements therein, in light of the circumstances under which they
         were made, not misleading; and, thereafter, Geron will as promptly as
         possible prepare (and, when completed, give notice to Manufacturer) a
         supplement or amendment to such Prospectus so that, as thereafter
         delivered to the purchasers of such Shares pursuant to the Registration
         Statement, such Prospectus will not contain an untrue statement of a
         material fact or omit to state any fact necessary to make the
         statements therein, in light of the circumstances under which they were
         made, not misleading; provided that upon such notification by Geron of
         the foregoing and instructing Manufacturer to cease to offer and sell
         Shares, Manufacturer will its best efforts to promptly suspend its
         offer and sale of Shares until Geron has notified Manufacturer that it
         has prepared a supplement or amendment to such Prospectus and delivered
         copies of such supplement or amendment to Manufacturer.

    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 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.

                                       4
<PAGE>

         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 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 COVENANTS 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 the
                  valid and legally binding obligations of Geron, enforceable
                  against Geron in accordance with its 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

                                       5
<PAGE>

                  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 to
                  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 ACKNOWLEDGMENTS 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 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 has 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.

                                       6
<PAGE>

                  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 except
                           as provided in Section 4 above. 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.

    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, demand 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:        Girindus America Inc.
                                             8560 Reading Rd
                                             Cincinnati , Ohio, 45215
                                             Attention: President
                                             Telephone:        (513) 679 - 3000
                                             Facsimile:        (513) 679 - 3053

    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 except to an entity controlling, under common
         control with or controlled by Manufacturer. Geron may not assign any of
         its 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 Delaware.

    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.

                                       7
<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 Project Orders 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.

                   REMAINDER OF PAGE INTENTIONALLY LEFT BLANK

                                       8
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Common Stock
Purchase Agreement as of the date first above written.

                                     Geron Corporation

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

                                     Girindus America Inc.

                                       /s/ Greg McParland
                                      ------------------------------------------
                                      By:     Greg McParland
                                      Title:  CEO

                                       9

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