Acts upstream of PAK1 to regulate the actin cytoskeleton, adhesion turnover and increase cell migration. Stimulates quiescent cells to reenter the cell cycle. Has no detectable GTPase activity but its high intrinsic guanine nucleotide exchange activity suggests it is constitutively GTP-bound. Plays a role in the regulation of cell morphology and cytoskeletal organization. Required in the control of cell shape (By similarity). Interacts with PAK3 (By similarity). Interacts with ARHGAP30 in a GTP-independent manner. In its GTP-loaded conformation, interacts with ARHGAP31. Interacts with PTK2B/PYK2 (By similarity). Localizes to podosomes in SRC-transformed cells. Tyrosine phosphorylated by SRC in response to PTK2B/PYK2 activation. Belongs to the small GTPase superfamily. Rho family.