Interpretation, Amendment and Enforcement. This letter agreement, [Exhibit A] and [Exhibit B] constitute the complete agreement between you and the Company, contain all of the terms of your employment with the Company and supersede any prior agreements, representations or understandings (whether written, oral or implied) between you and the Company. This letter agreement may not be amended or modified, except by an express written agreement signed by both you and a duly authorized officer of the Company. The terms of this letter agreement and the resolution of any disputes as to the meaning, effect, performance or validity of this letter agreement or arising out of, related to, or in any way connected with, this letter agreement, your employment with the Company or any other relationship between you and the Company (the “Disputes”) will be governed by California law, excluding laws relating to conflicts or choice of law. You and the Company submit to the exclusive personal jurisdiction of the federal and state courts located in San Francisco, California, in connection with any Dispute or any claim related to any Dispute.

Interpretation, Amendment and Enforcement. This letter agreement and the Confidentiality Agreement constitute the complete agreement between you and the Company regarding your employment with the Company, contain all of the terms of your employment with the Company and supersede any prior agreements, representations or understandings (whether written, oral or implied) between you and the Company. This letter agreement may not be amended or modified, except by an express written agreement signed by both you and a duly authorized officer of the Company, although your job duties, title, reporting relationship, compensation and benefits may change from time to time. In the event the terms of this letter contradict or are in any way different from the terms contained any other document(s) provided by the Company, this letter shall control unless otherwise expressly set forth in such other document(s). The terms of this letter agreement and the resolution of any disputes as to the meaning, effect, performance or validity of this letter agreement or arising out of, related to, or in any way connected with, this letter agreement, your employment with the Company or any other relationship between you and the Company will be governed by California law, excluding laws relating to conflicts or choice of law.

Governing Law, Interpretation and Enforcement. This Agreement shall, for all purposes, be construed, governed and enforced in accordance with the laws of the State of Texas without regard to Texas’ principles of conflicts of law. If any provision of this Agreement should need to be interpreted or construed, I and You agree that the entity interpreting or constructing this Agreement shall not apply a presumption against one party by reason of the rule of construction that a document is to be construed more strictly against the party who prepared the document. Additionally, any action to enforce the terms of this Agreement shall be commenced in [[Address A:Address]]. Both parties consent to personal jurisdiction in federal and state courts in [[Address A:Address]].

Governing Law. All questions concerning the construction, validity, enforcement and interpretation of this Amendment shall be determined pursuant to the Governing Law provision of the New Warrants.

Interpretation, Amendment and Enforcement. This letter agreement and [Exhibit A] constitute the complete agreement between you and the Company, contain all of the terms of your employment with the Company and supersede any prior agreements, representations or understandings (whether written, oral or implied) between you and the Company. This letter agreement may not be amended or modified, except by an express written agreement signed by both you and a duly authorized officer of the Company. The terms of this letter agreement and the resolution of any disputes as to the meaning, effect, performance or validity of this letter agreement or arising out of, related to, or in any way connected with, this letter agreement, your employment with the Company or any other relationship between you and the Company will be governed by California law, excluding laws relating to conflicts or choice of law.

Interpretation, Amendment and Enforcement. This letter and the Restrictive Covenant Agreements constitute the complete agreement between you and the Company, contain all of the terms of your employment with the Company and supersede any prior agreements, representations or understandings (whether written, oral or implied) between you and the Company. The terms of this letter and the resolution of any disputes as to the meaning, effect, performance or validity of this letter or arising out of, related to, or in any way connected with, this letter, your employment with the Company or any other relationship between you and the Company (the “Disputes”) will be governed by Massachusetts law, excluding laws relating to conflicts or choice of law. You and the Company submit to the exclusive personal jurisdiction of the federal and state courts located in the Commonwealth of Massachusetts in connection with any Dispute or any claim related to any Dispute.

Interpretation, Amendment and Enforcement. This letter agreement and [Exhibit A] constitute the complete agreement between you and the Company, contain all of the terms of your employment with the Company and supersede any prior agreements, representations or understandings (whether written, oral or implied) between you and the Company. This letter agreement may not be amended or modified, except by an express written agreement signed by both you and a duly authorized officer of the Company. The terms of this letter agreement and the resolution of any disputes as to the meaning, effect, performance or validity of this letter agreement or arising out of, related to, or in any way connected with, this letter agreement, your employment with the Company or any other relationship between you and the Company shall be governed by California law, excluding laws relating to conflicts or choice of law.

Interpretation, Amendment and Enforcement. This letter agreement and [Exhibit A] constitute the complete agreement between you and the Company, contain all of the terms of your employment with the Company and supersede any prior agreements, representations or understandings (whether written, oral or implied) between you and the Company. This letter agreement may not be amended or modified, except by an express written agreement signed by both you and a duly authorized officer of the Company. The terms of this letter agreement and the resolution of any disputes as to the meaning, effect, performance or validity of this letter agreement or arising out of, related to, or in any way connected with, this letter agreement, your employment with the Company or any other relationship between you and the Company (the “Disputes”) will be governed by California law, excluding laws relating to conflicts or choice of law. You and the Company submit to the exclusive personal jurisdiction of the federal and state courts located in San Francisco, California, in connection with any Dispute or any claim related to any Dispute.

Interpretation, Amendment and Enforcement. This letter agreement, together with the Employee Confidential Information and Inventions Assignment Agreement, any Change in Control Severance Plan documentation previously executed by you, and any Option Agreements that you entered into with the Company or any subsidiary thereof constitutes the complete agreement between you and the Company, contains all of the terms of your employment with the Company and supersedes any prior agreements, representations or understandings (whether written, oral or implied) between you and the Company. It is entered into without reliance on any promise or representation, written or oral, other than those expressly contained herein, and it supersedes any other agreements, promises, warranties or representations concerning its subject matter. Changes in your employment terms, other than those changes expressly reserved to the Company’s discretion in this letter, require an express written modification signed by both you and a duly authorized officer of the Company. If any provision of this offer letter agreement is determined to be invalid or unenforceable, in whole or in part, this determination shall not affect any other provision of this offer letter agreement and the provision in question shall be modified so as to be rendered enforceable in a manner consistent with the intent of the parties insofar as possible under applicable law. This letter may be delivered and executed via facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of 2000, Uniform Electronic Transactions Act or other applicable law) or other transmission method and shall be deemed to have been duly and validly delivered and executed and be valid and effective for all purposes. * * * * *

Jurisdiction. All questions concerning the construction, validity, enforcement and interpretation of this Amendment shall be determined in accordance with the provisions of the Securities Purchase Agreement.