Molecular model (CPK representation) of Ras-RasGAP complex. The Ras nit is in cyan, RasGAP in yellow, GDP green. Ras proteins are the smallest G proteins comprising the common core of the G protein fold, binding GDP/GTP and having intrinsic GTPase activity. GTPase activating protein (GAP) stimulates GTPase of normal but not oncogenic RAS P21. PDB code: 1wq1.