GTPases represent a large family of proteins involved in a wide variety of cellular processes. They function as switches in which they are "on" in the GTP bound state and "off" in the GDP bound state. The "on" and "off" states are regulated by proteins which interact with the GTPases and enhance their rate of either GTP hydrolysis or GDP-GTP exchange. Thus far, GTPases have been shown to be involved in protein synthesis, signal transduction, control of cell growth, and intracellular transport.