Adapter molecule crk is a protein in humans that is encoded by CRK gene. Adapter molecule crk is a protein in humans that is encoded by CRK gene. Isoform Crk-II: Regulates cell adhesion, spreading and migration. Mediates attachment-induced MAPK8 activation, membrane ruffling and cell motility in a Rac-dependent manner. Involved in phagocytosis of apoptotic cells and cell motility via its interaction with DOCK1 and DOCK4. May regulate the EFNA5-EPHA3 signaling.