Figure 1.

Intracellular signaling model of Rho GTPases in receptor-initiated pathways. Most Rho GTPases cycle between the GDP-bound, inactive state and the GTP-bound, active state. The GTP binding and GTP hydrolysis cycle is tightly regulated by Rho guanine nucleotide exchange factors (GEFs), Rho GTPase-activating proteins (GAPs), and Rho GDIs (GDP dissociation inhibitors), which also control their intracellular localization patterns. On activation by cytokine, chemokine, growth factor, or adhesion molecules, the GTP-bound Rho GTPases can transiently interact with a large panel of effector proteins to transduce signals that affect cell cycle, survival, transcription, adhesion, and cytoskeleton machineries.