May mediate attachment-induced MAPK8 activation, membrane ruffling and cell motility in a Rac-dependent manner. Involved in phagocytosis of apoptotic cells and cell motility (By similarity). Involved in cell branching and adhesion (By similarity). May regulate the EFNA5-EPHA3 signaling (By similarity). Interacts with ABL1, C3G, SOS, MAP4K1, MAPK8 and DOCK1 via its first SH3 domain. Interacts with BCAR1, CBL, PXN and GAB1 via its SH2 domain upon stimulus-induced tyrosine phosphorylation. Interacts with several tyrosine-phosphorylated growth factor receptors such as EGFR, PDGFR and INSR via its SH2 domain (By similarity). Translocated to the plasma membrane upon cell adhesion. Phosphorylated on Tyr-222 upon cell adhesion. Results in the negative regulation of the association with SH2- and SH3-binding partners, possibly by the formation of an intramolecular interaction of phosphorylated Tyr-222 with the SH2 domain. This leads finally to the down-regulation of the Crk signaling pathway (By similarity). Proline isomerization at Pro-238 by PPIA acts as a switch between two conformations: an autoinhibitory conformation in the cis form, where the tandem SH3 domains interact intramolecularly, and an activated conformation in the trans form. Belongs to the CRK family.