The story of rapamycin is a pharmaceutical fairytale. Discovered as an 
antifungal activity in a soil sample collected on Easter Island, this 
macrocyclic lactone and its derivatives are now billion dollar drugs, used in, 
and being evaluated for, a number of clinical applications. Taking advantage of 
its antifungal property, the molecular Target Of Rapamycin, TOR, was first 
described in the budding yeast Saccharomyces cerevisiae. TORs encode large, 
Ser/Thr protein kinases that reside in two distinct, structurally and 
functionally conserved, multi-protein complexes. In yeast, these complexes 
coordinate many different aspects of cell growth. TOR complex 1, TORC1, promotes 
protein synthesis and other anabolic processes, while inhibiting macroautophagy 
and other catabolic and stress-response processes. TORC2 primarily regulates 
cell polarity, although additional readouts of this complex are beginning to be 
characterized. TORC1 appears to be activated by nutrient cues and inhibited by 
stresses and rapamycin; however, detailed mechanisms are not known. In contrast, 
TORC2 is insensitive to rapamycin and physiological regulators of this complex 
have yet to be defined. Given the unsurpassed resources available to yeast 
researchers, this simple eukaryote continues to contribute to our understanding 
of eukaryotic cell growth in general and TOR function in particular.