PTP_background Kser PTP_pY789 rho_srco srco rho_srca srca src_background rho_srcc srcc Cbp_P kCSKon CSK_cytoplasm kCSKoff Cbp_P_CSK default kCbp src_activity Cbp default default kPTP src_activity p3 PTP p2 PTP_pY789 k2 ptp_activity srci k1 Cbp_P_CSK srco default k3 src_activity srco p1 srca default k1 Cbp_P_CSK srca k2 ptp_activity srcc default default k4 p1 srcc