The regulator of G-protein signaling 4 (RGS4) is a protein of the class of GTPase activating proteins (GAP) and shows no GTPase activity by itself. Instead, RGS proteins are negative regulators of G alpha subunits of heterotrimeric G proteins (Gi,  Go, and Gq)[1]. Because its functions is inherently part of the well functioning of these heterotrimeric G proteins  (EC 3.6.5.1), inhibitors of RGS4 are listed in this particular section.