ABSTRACT
Acknowledgments ....................................................................................................84 References ................................................................................................................84
Small RhoGTPases are molecular switches that are involved in a variety of cellular processes, including reorganization of the actin cytoskeleton and microtubule network, cell cycle progression, transcriptional control, and immune responses such as phagocytosis.1 In resting cells, the RhoGTPases Rac, Cdc42, and RhoA are sequestered in the cytosol by the guanosine 5 diphosphate (GDP) dissociation inhibitor, RhoGDI, in their inactive, GDP-bound form. Exposure of cells to pathogens or soluble stimuli including pathogen-associated molecular patterns (PAMPs) or growth factors initiates the activation of guanine nucleotide exchange factors (GEFs) that will cause the exchange of GDP to GTP and the dissociation of RhoGDI from RhoGTPases.2 As a result, RhoGTPases are fully active and can bind to specific effector proteins to modulate cellular events. Cell type, as well as stimulus-specific activation of RhoGTPases, is ensured by the activation of only a limited subset of GEFs and by the interaction with selective effectors downstream.
