GENSTAR THERAPEUTICS CORPORATION EMPLOYEE STOCK PURCHASE PLAN  1.    *Purpose*.    This Employee StockPurchase Plan (the “Plan”) is intended to serve as an incentive to and to encourage stock ownership by certain eligible employees of Genstar Therapeutics Corporation, a Delaware corporation, and certain affiliates as set forth below (the“Corporation”), so that they may acquire or increase their proprietary interest in the success of the Corporation, and to encourage them to remain in the service of the Corporation. This Plan is intended to qualify as an employee stockpurchase plan, as defined in Section 423 of the Internal Revenue Code of 1986, as amended (the “Code”).  2.    *Administration*.  2.1 *Committee*.    ThePlan shall be administered by the Board of Directors of the Corporation (“Board of Directors”) or a committee of two or more members appointed by the Board of Directors (the “Committee”) who are Non-Employee Directors, as suchterm is defined in Rule 16b-3 promulgated under Section 16 of the Securities Exchange Act of 1934, as amended, and outside directors, as defined in Treasury Regulations § 1.162-27(e)(3). The Committee shall select one of its members as Chairmanand shall appoint a Secretary, who need not be a member of the Committee. The Committee shall hold meetings at such times and places as it may determine and minutes of such meetings shall be recorded. Acts by a majority of the Committee in a meetingat which a quorum is present and acts approved in writing by a majority of the members of the Committee shall be valid acts of the Committee.  2.2 *Term*.    If the Board of Directors selects a Committee, the members of the Committee shall serve on the Committee for a period of time as determined by the Board of Directors and shallbe subject to removal by the Board of Directors at any time. The Board of Directors may terminate the function of the Committee at any time and resume all powers and authority previously delegated to the Committee.  2.3 *Authority*.    The Committee shall have sole discretion and authority to prescribe, amend and rescindthe rules and regulations relating to the Plan and to make all other determinations necessary and advisable for the administration of the Plan.  2.4 *Interpretation*.    The interpretation and construction by the Committee of any provisions of the Plan or of any option granted under itshall be final and binding on all parties having an interest in this Plan or any option granted hereunder. No member of the Committee shall be liable for any action or determination made in good faith with respect to the Plan or any option grantedunder the plan.  2.5 *Agent*.    The Committee may employ such legal counsel,consultants, brokers and agents as it may deem desirable for the administration of the Plan and may rely upon any opinion 1 
 received from any such counsel or consultant and any computation received from any suchconsultant, broker or agent. The Committee may, in its sole discretion, designate an agent (“Agent”) to administer the Plan, keep records, send statements of account to employees and to perform other duties relating to the Plan, as theCommittee may request from time to time.  3.    *Eligibility*.  3.1 *General*.    Except as otherwise provided in Section 3.2, all regular employees of the Corporation, orany “parent” or “subsidiary” corporation of the Corporation, as defined in Section 424 of the Code (“Parent” or “Subsidiary”) (i) whose customary employment is at least 20 hours per week and (ii) who areemployed on an Enrollment Date (as defined below) are eligible to participate (“Eligible Employee”). All Eligible Employees who elect to participate in this Plan shall have the same rights and privileges except as provided in Section 3.5.Notwithstanding the above, employees of a Parent or Subsidiary shall only be Eligible Employees if the Committee designates such corporation as a participant. For purposes of this Plan, the term “Corporation” shall also include any Parentor Subsidiary, if applicable.  3.2 *Excluded Eligible Employees*.    Notwithstandingany other provision in this Agreement, no employee can be granted the right to purchase stock under this Plan if such employee (i) is customarily not employed by the Corporation for more than five months a year, or (ii) immediately after the rightto purchase such stock is granted, owns stock possessing 5% or more of the total combined voting power or value of all classes of the Corporation’s stock (or of the Corporation’s Parent or Subsidiary.) For purposes of determining stockownership, the rules of Section 424(d) of the Code shall apply, and stock which the employee may purchase under outstanding options, including rights to purchase stock under this Plan, shall be treated as stock owned by the employee.  3.3 *Semi-Annual Offerings*.    Until the Plan is terminated, the Plan will be implemented bysemi-annual offerings of the right to purchase the Corporation’s common stock pursuant to this Plan (the “Offerings”) beginning on the 1st day of May and the 1st day of November in each year and terminating on April 30 ofthe second year thereafter (24 months) for the Offering beginning May 1 and on October 31 of the second year thereafter (24 months) for the Offering beginning November 1 of such year (“Offering Period”); provided, however, that eachsemi-annual Offering may, in the discretion of the Committee exercised prior to the commencement thereof, be changed to semi-annual or annual Offerings with a shorter duration. Each May 1st and November 1st in an Offering Period shall be an“Enrollment Date.” As used in the Plan, “Entry Date” means the May 1 or November 1, as the case may be, on which the particular Offering Period begins and “Termination Date” means the April 30 or October 31, as the casemay be, on which the particular Offering Period terminates. 2 
 3.4 *Participation*.  3.4.1 Eligible Employees who wish to participate in the Plan shall execute a form (“Enrollment Form”) to be furnished by theCorporation, indicating that they authorize and instruct the Corporation to deduct from their semi-monthly pay a specified percentage of their respective Base Compensation (as defined below), to be applied to the purchase of stock pursuant to thisPlan for each individual’s account. Enrollment Forms will be effective as of the next Enrollment Date. All payroll deductions made for a participant shall be credited to his account under the Plan. A participant may not make any separate cashpayment into such account. Subject to Section 3.5, each participant may designate any whole percentage of his or her base salary or any fixed dollar amount per pay period to be contributed to the Plan on his or her behalf; provided that any fixeddollar amount shall not exceed 15% of such Eligible Employee’s Base Compensation for such Offer. Upon the participant’s written request to the Corporation, the amount of the payroll deduction will be changed as of the next Enrollment Date(as defined above) following such request. Any election by a member to decrease his or her payroll deductions to 0% shall be deemed to be an election to withdraw from the Plan effective immediately following the purchase of shares on the nextTermination Date. Nonparticipating employees who are eligible or become eligible may execute payroll deduction authorizations and become participants in the Plan as of the Enrollment Date after which they first satisfy the eligibility requirementsset forth in Section 3.1. The election by the participant must be received prior to the Enrollment Date. Payroll deductions will commence with pay checks issued not later than the next pay period after the Enrollment Date following receipt of theexecuted Enrollment Form.  3.4.2 Re-Enrollment Upon Expiration of Offering Period. At the end of aparticipant’s then-current Offering Period, the participant automatically shall be enrolled in the next succeeding Offering Period (a “Re-enrollment”) unless, in a manner and at a time specified by the Corporation, but in no eventlater than the day before the first day of such succeeding Offering Period, the participant notifies the Corporation in writing of the participant’s desire not to be so enrolled. Re-enrollment shall be at the same percentage of contributions asthe participant’s prior participation unless the participant by timely written notice changes the percentage of contribution. No participant shall be automatically re-enrolled whose participation terminates by operation of Section 3.11 or who,during the preceding Offering Period, has reduced his or her percentage of contribution to 0% or has notified the Corporation in writing of the participant’s withdrawal from participation in the Plan.  3.5 *Limitation on Participation*.    An Eligible Employee may not elect to contribute to the Plan more thanthe lesser of $25,000 or 15% of such Eligible Employee’s Base Compensation (as defined below) for the calendar year. “Base Compensation” means the base compensation paid in cash to a participant by the Corporation, including salariesand wages, but excluding bonuses, incentive compensation, commissions, overtime pay, moving or relocation allowances, car allowances, imputed income attributable to cars, taxable fringe benefits and similar items. In addition, a participant may notelect to make such contributions to the Plan which would permit stock with a fair market value exceeding $25,000 to be purchased for his or her account in any 3 
 calendar year under all stock purchase plans of the Corporation as determined under Section 423of the Code. For this purpose, the fair market value of the stock will be determined at the time that the participant is granted the right to purchase Stock. All share amounts set forth herein are subject to adjustment as provided in Section 5. 3.6 *Purchase of Stock*.    Unless a participant gives written notice to theCorporation as hereinafter provided, a participant’s option to acquire stock with payroll deductions made during any Offering Period will be deemed to have been exercised automatically on the Termination Date applicable to such Offering for thepurchase of the number of full shares of stock which the accumulated payroll deductions in his account at that time will purchase at the applicable option price (but not in excess of the number of shares, for which options have been granted to theemployee pursuant to Section 4.1), and any excess in the participant’s account at that time will be returned to the participant. Any unexercised options on any Termination Date shall terminate and be null and void.  3.7 *Delivery of Stock*.    As promptly as practicable after the Termination Date of each Offering, theCorporation will deliver to each participant, as appropriate, the stock purchased upon exercise of an option.  3.8 *Discontinuing Payroll Deductions*.    If a participant wishes to discontinue employee contributions entirely, he or she may do so by filing a new enrollment form at any time. Payroll withholding shall cease assoon as reasonably practicable after such form has been received by the Corporation. Discontinuation of payroll deductions shall be treated as an election to withdraw from the Plan and amounts standing to the Participant’s credit prior to hisor her election to discontinue contributions shall be distributed to him or her in accordance with Section 3.9.  3.9 *Withdrawal or Termination*.    A participant may elect to withdraw from the Plan by filing the prescribed form with the Corporation at any time. If the participant withdraws from the Plan, the participant willbe returned all accumulated payroll deductions, without interest. A participant who discontinues contributions to the Plan under Section 3.8, or withdraws from the Plan under this Section may again become a participant, if he or she is then anEligible Employee, by following the procedure described in Section 3.4.  3.10 *Payment ofInterest*.    No interest will be paid or allowed on any money paid into the Plan or credited to the account of any participant.  3.11 *Termination*.    In the event of a participant’s death or termination of employment, the discontinuance of the Plan by theCorporation, the election of the employee to withdraw from the Plan for any reason, or in the event the employee is no longer an Eligible Employee, all of such participant’s accumulated payroll deductions contributed to the Plan during theOffering Period in which such withdrawal or termination occurs will be distributed, without interest, to his or her name or order, or in the event of death, to the name of his or her legal representative, as promptly as practicable. 4 
 3.12 *Limitation on Subscriptions*.    The totalnumber of shares of stock available for purchase under the Plan is 1,000,000 shares, subject to adjustment as set forth in Section 5. In the event that the aggregate number of shares that all participants elect to purchase on a Termination Dateexceeds the maximum number of shares remaining available for issuance under this Section, then the number of shares to which each participant is entitled shall be determined by multiplying the number of shares available for issuance by a fraction,the numerator of which is the number of shares that such participant has elected to purchase and the denominator of which is the number of shares that all participants have elected to purchase.  3.13 *Expenses*.    All costs of maintaining records and executing transfers will be borne by the Corporation.  3.14 *Fair Market Value*.    The fair market value of a share of stock on any relevant date shall bedetermined in accordance with the following provisions:  3.14.1 If the stock at the time is neither listed noradmitted to trading on any stock exchange nor traded in the over-the-counter market, then the fair market value shall be the value of the stock as determined by the Board of Directors in their last valuation of the Stock, after taking into accountsuch factors as the Board of Directors shall deem appropriate.  3.14.2 If the stock is not at the time listedor admitted to trading on any stock exchange but is traded in the over-the-counter market, the fair market value shall be the mean between the highest bid and lowest asked prices (or, if such information is available, the closing selling price) ofone share of stock on the date in question in the over-the-counter market, as such prices are reported by the National Association of Securities Dealers through its NASDAQ system or any successor system. If there are no reported bid and asked prices(or closing selling price) for the stock on the date in question, then the mean between the highest bid price and lowest asked price (or the closing selling price) on the last preceding date for which such quotations exist shall be determinative offair market value.  3.14.3 If the stock is at the time listed or admitted to trading on any stock exchange,then the fair market value shall be the closing selling price of one share of stock on the date in question on the stock exchange determined by the Committee to be the primary market for the stock, as such price is officially quoted in the compositetape of transactions on such exchange. If there is no reported sale of stock on such exchange on the date in question, then the fair market value shall be the closing selling price on the exchange on the last preceding date for which such quotationexists.  4.    *Granting of Options*.  4.1 *Number of Option Shares*.    Subject to Section 3.5, on the Entry Date of each Offering, a participating employee shall be deemed to havebeen granted an option to purchase a 5 
 maximum number of shares of the stock of the Corporation equal to $75,000 divided by the fairmarket value of a share determined at the grant date of such purchase right. The market value of the Corporation’s stock shall be determined as provided in Section 3.14.  4.2 *Option Price*.    The option price of stock purchased with payroll deductions made during an Offering for a participant therein shall bethe lower of (i) 85% of the fair market value of the stock of the Corporation on the Entry Date or (ii) 85% of the fair market value on the date of purchase as set forth in Section 3.6.  5.    *Adjustments upon Changes in Capitalization*.  5.1 *Subdivision or Consolidation*.    Subject to any required action by shareholders of the Corporation, the number of shares of stock covered by each out­standing option, and theexercise price thereof, shall be proportionately adjusted for any increase or decrease in the number of issued shares of stock of the Corporation resulting from a subdivision or consolidation of shares or the payment of a stock dividend (but only onthe stock) or any other increase or decrease in the number of such shares effected without receipt of consideration by the Corporation including, but not limited to, a stock split, reverse stock split, recapitalization, combination orreclassification. Any fraction of a share subject to an option that would otherwise result from an adjustment pursuant to this Section shall be rounded downward to the next full number of shares without other compensation or consideration to theholder of such option.  5.2 *Capital Transactions*.    Upon a sale or exchange of allor substantially all of the assets of the Corporation, a merger or consolidation in which the Corporation is not the surviving corporation, a merger, reorganization or consolidation in which the Corporation is the surviving corporation andshareholders of the Corporation exchange their stock for securities or property, a liquidation of the Corporation or similar transaction (“Capital Transaction”), this Plan and each option to purchase stock issued under this Plan shallterminate, unless such options are assumed by a successor corporation in the Capital Transaction, on the date of such Capital Transaction; provided, however, that unless the outstanding options are assumed by a successor corporation in the CapitalTransaction, then the day prior to the date of the Capital Transaction shall be a Termination Date and the funds held in each participant’s account shall be used to purchase the number of full shares of stock at the applicable option price (butnot in excess of the number of shares for which options have been granted to the participant pursuant to Section 4.1) and any excess in the participant’s account at that time will be returned to the participant.  5.3 *Adjustments*.    To the extent that the foregoing adjustments relate to stock or securities of theCorporation, such adjustments shall be made by the Committee, whose determination in that respect shall be final, binding and conclusive.  5.4 *Ability to Adjust*.    The grant of an option pursuant to the Plan shall not affect in any way the right or power of the Corporation to make adjustments, reclassifications, 6 
reorganizations or changes of its capital or business structure or to merge, consolidate, dissolve, liquidate, sell or transfer all orany part of its business or assets.  5.4 *Notice of Adjustment*.    Whenever theCorporation shall take any action resulting in any adjustment provided for in this Section, the Corporation shall forthwith deliver notice of such action to each participant, which notice shall set forth the number of shares subject to the optionand the exercise price thereof resulting from such adjustment.  5.5 *Limitation onAdjustments*.    Any adjustment, assumption or substitution shall not provide any participant with any additional benefit under his or her option and shall comply with Section 425 of the Code, if applicable.  6.    *Transferability*.    Options granted under this Plan may not be sold, pledged, assignedor transferred in any manner other than by will or by the laws of descent and distribution, and may be exercised during the lifetime of a participant only by such participant. Any transfer in violation of this provision shall void such option. Nooption shall be pledged or hypothecated in any way, nor shall any option be subject to execution, attachment or similar process.  7.    *Rights as a Shareholder*.    A participant shall have no rights as a shareholder with respect to any stock underlying any option until the date of the issuance to such participant acertificate for such shares. No adjustment shall be made for dividends (ordinary or extra­ordinary, whether in cash, securities or other property) or distributions or other rights for which the record date is prior to the date such stockcertificate is issued, except as provided in Section 6.  8.    *No Right ofEmployment*.    Neither the grant nor exercise of any option nor anything in this Plan shall impose upon the Corporation or any other corporation any obligation to employ or continue to employ any participant. The right of theCorporation and any other corporation to terminate any employee shall not be diminished or affected because an option has been granted to such employee.  9.    *Amendment or Termination of the Plan*.    The Board of Directors of the Corporation may, subject to any requested shareholder approval, amend, suspend, discontinueor terminate the Plan, or revise or amend it in any respect whatsoever. The Board of Directors of the Corporation shall be entitled to terminate the Plan at anytime in their sole discretion. Upon termination of the Plan, all accumulated payrolldeductions contributed to the Plan during the Offering Period in which such termination occurs will be distributed without interest to participants and participants’ options to purchase stock under this Plan will be canceled, as of the date ofthe Plan termination.  10.    *Term of Plan*.    This Plan is effective on the datethe Plan is adopted by the Board of Directors and options may be granted pursuant to the Plan from time to time until March 31, 2011.  11.    *Approval of Board of Directors and Shareholders*.    The Plan shall not take effect until approved by the Board of Directors of the Corporation. This Plan shall be approved by a vote ofthe 7 
 shareholders by April 11, 2002. In the event such shareholder vote is not obtained, all options granted hereunder,whether vested or unvested, shall be rescinded and shall be null and void.  12.    *Application ofFunds*.    The proceeds received by the Corporation from the sale of stock pursuant to options may be used for general corporate purposes.  13.    *Reservation of Shares*.    The Corporation, during the term of this Plan, shall at all times reserve and keep available such numberof shares of stock as shall be sufficient to satisfy the requirements of the Plan.  14.    *No Obligationto Exercise Option*.    The granting of an option shall not impose any obligation upon the participant to exercise such option.  15.    *Withholding Taxes*.    Notwithstanding anything else to the contrary in the Plan, the exercise of any option shall be conditioned upon payment by such participantin cash, or other provisions satisfactory to the Committee of all local, state and federal withholding taxes applicable, in the Committee’s judgment, to the exercise or to later disposition of shares acquired upon exercise of an option. 16.    *Securities Laws Compliance*.    Notwithstanding anything contained herein,the Corporation shall not be obligated to grant any option under this Plan or to sell, issue or effect any transfer of any share pursuant to this Plan unless such grant, sale, issuance or transfer is at such time effectively (i) registered or exemptfrom registration under the Act, and (ii) qualified or exempt from qualification under the California Corporate Securities Law of 1968 and any other applicable state securities laws. As a condition to exercise of any option, each participant shallmake such representations as may be deemed appropriate by counsel to the Corporation for the Corporation to use any available exemption from registration under the Act or qualification under any applicable state securities law.  17.    *Restrictive Legends*.    The certificates issued pursuant to this Plan shall bear anyapplicable legends that may be desirable or necessary as determined in the sole and absolute discretion of the Corporation.  18.    *Notices*.    Any notice to be given under the terms of this Agreement shall be addressed to the Corporation in care of its Secretary at its principal office, and any notice to be given toparticipant shall be addressed to such participant at the address maintained by the Corporation for such person or at such other address as the participant may specify in writing to the Corporation.  19.    *Effect of Plan*.    The provisions of the Plan shall, in accordance with its terms, be bindingupon, and inure to the benefit of, all successors of each employee participating in the Plan, including, without limitation, such employee’s estate and the executors, administrators or trustees thereof, heirs and legatees, and any receiver,trustee in bankruptcy or representative of creditors of such employee. 8 
 20.    *Arbitration*.    In the event of anydispute between the Corporation and a participant regarding this Plan, the dispute and any issue as to the arbitrability of such dispute, shall be settled to the exclusion of a court of law, by arbitration in San Diego, California, by a panel ofthree arbitrators (each party shall choose one arbitrator and the third shall be chosen by the two arbitrators so selected) in accordance with the Commercial Arbitration Rules of the American Arbitration Association then in effect. The decision of amajority of the arbitrators shall be final and binding upon the parties. All costs of the arbitration and the fees of the arbitrators shall be allocated between the parties as determined by a majority of the arbitrators, it being the intention ofthe parties that the prevailing party in such a proceeding be made whole with respect to its expenses.  21.    *Governing Law*.    This Agreement shall be governed by the laws of the State of California.  22.    *Descriptive Headings*.    Titles to Sections are solely for information purposes.  23.    *Information*.    All participants in the Plan shall be distributed financial statements of the Corporation at least annually. 24.    *Rule 16(b)*.    To the extent required, the Plan is intended to complywith Rule 16(b)(3) of the Exchange Act as then in effect or any successor provisions (“Rule 16(b)(3)”) and the Committee shall interpret and administer the provisions of the Plan in a manner consistent therewith. Any provisionsinconsistent with Rule 16(b)(3) shall be inoperative and shall not affect the validity of the Plan. The Committee may establish and adopt written administrative guidelines, designed to facilitate compliance with Section 16(b) of the Exchange Act andRule 16(b)(3), as it may deem necessary or proper for the administration and operation of the Plan and the transaction of business thereunder.  As adopted by the Board of Directors effective April 12, 2001.   GENSTAR THERAPEUTICS CORPORATION,  a Delaware corporation   By:                                              Chief Executive Officer 9