The members of the Rho family of small GTPases are involved in an array of cellular processes, including regulation of the actin cytoskeleton, cell polarity, microtubule dynamics, membrane transport, and transcription factor activity. Recent findings have implicated the Rho-proteins as key regulators of angiogenesis, modulating a diversity of cellular processes, including vascular permeability, extracellular matrix remodeling, migration, proliferation, morphogenesis, and survival.