This excerpt taken from the TPTX 10-K filed Mar 29, 2007.
10. AWARD NOT A SERVICE CONTRACT. Your Award is not an employment or service contract, and nothing in your Award will be deemed to create in any way whatsoever any obligation on your part to continue in the service of the Company or an Affiliate, or on the part of the Company or an Affiliate to continue such service. In addition, nothing in your Award will obligate the Company or an Affiliate, their respective stockholders, boards of directors or employees to continue any relationship that you might have as an employee of the Company or an Affiliate.