David was a MD/PhD student in the lab and studied the mechanism of action of the Tor signaling pathway in yeast and mammalian cells. This is the pathway that is blocked by rapamycin. He found along with Calvin Kuo that rapamycin blocked the activation of p70S6 kinase, hence making the first steps in showing that this pathway regulated protein synthesis. He is presently on the faculty at Stanford University Hospital. His e.mail address is fiorentino@stanford.edu