Function: Small GTP-binding protein which cycles between an inactive GDP-bound and an active GTP-bound form, and the rate of cycling is regulated by guanine nucleotide exchange factors (GEF) and GTPase-activating proteins (GAP). Required for normal cytokinesis and cilia signaling. Requires assistance from GTPase-activating proteins (GAPs) like RP2 and PDE6D, in order to cycle between inactive GDP-bound and active GTP-bound forms. Required for targeting proteins such as NP/HP3 to the ciliary membrane by releasing myristoylated NP/HP3 from UNC119B cargo adapter into the cilium. Does not act as an allosteric activator of the cholera toxin catalytic subunit.