RGS5, also known as regulator of G-protein signaling 5, binds directly to activated G alpha subunits and act as GTPase-activating proteins(GAPs) to attenuate and/or modulate hormone and neurotransmitter receptor-initiated signaling by both G alpha-GTP and G beta gamma. Vascular endothelial cells express the RGS protein RGS5, where it correlates with capillary morphogenesis, thus rendering it a candidate gene involved in capillary growth, angiogenesis, and also potentially the pathophysiology of stroke.