Rnd3,also known as RhoE,belongs to the Rnd subclass of the Rho family of small guanosine triphosphate (GTP)-binding proteins. Rnd proteins are unique due to their inability to switch from a GTP-bound to GDP-bound conformation. The basic role of Rnd3 is to report as an endogenous antagonist of RhoA signaling-mediated actin cytoskeleton dynamics,which specifically contributes to cell migration and neuron polarity. Rnd3 also plays a critical role in arresting cell cycle distribution,inhibiting cell growth,and inducing apoptosis and differentiation.