Fox Chase Cancer Center, 7701 Burholme Ave, Philadelphia, PA 19111, USA. J_Chernoff@fccc.edu
Cdc42 and Rac--ancient, highly conserved, small GTPases--mediate extracellular signals, triggering changes in transcription and in the actin cytoskeleton. Although dozens of proteins act downstream of these GTPases, a comparison of effector proteins from evolutionarily diverse organisms suggests that six groups of proteins serve as the core machinery for signaling from Cdc42 and Rac.