GTP + H2O = GDP + H(+) + phosphate Alternates between an inactive form bound to GDP and an active form bound to GTP. Activated by a guanine nucleotide-exchange factor (GEF) and inactivated by a GTPase-activating protein (GAP). This p21 transforming protein was generated by a transduction of rodent cellular K-Ras-2 gene. Belongs to the small GTPase superfamily. Ras family.