Involved in cell branching and adhesion mediated by BCAR1-CRK-RAPGEF1 signaling and activation of RAP1. Regulates cell adhesion, spreading and migration (PubMed:31311869). 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 (PubMed:19004829). May regulate the EFNA5-EPHA3 signaling (By similarity). Component of a complex comprised of SH2D3C, BCAR1/CAS, and CRK (PubMed:12432078). Within the complex, interacts with SH2D3C (via C-terminus), and BCAR1/CAS (PubMed:12432078). Found in a complex with ABL1, ABL2, CRK and UNC119; leading to the inhibition of CRK phosphorylation by ABL kinases (PubMed:19381274). Interacts with ABL1, C3G, DOCK3, DOCK5, MAP4K1, MAPK8 and SOS via its first SH3 domain. Interacts (via SH2 domain) with BCAR1, CBL, CBLB, PXN, IRS4 and GAB1 upon stimulus-induced tyrosine phosphorylation. Interacts (via SH2 domain) with several tyrosine-phosphorylated growth factor receptors such as EGFR and INSR. Interacts with FLT1 (tyrosine-phosphorylated). Interacts with DOCK1 and DOCK4. Interacts with SHB. Interacts with PEAK1. Interacts with FASLG. Part of a collagen stimulated complex involved in cell migration composed of CDC42, CRK, TNK2 and p130cas/BCAR1. Interacts (via SH2 domain) with the 'Tyr-9' phosphorylated form of PDPK1. Interacts with CBLC. Interacts (via SH2 domain) with PDGFRA (tyrosine phosphorylated) and PDGFRB (tyrosine phosphorylated) (PubMed:10733900). Interacts with EPHA3 (phosphorylated); upon activation of EPHA3 by the ligand EFNA5 and EPHA3 tyrosine kinase activity-dependent and mediates EFNA5-EPHA3 signaling through RHOA GTPase activation (PubMed:11870224). Interacts with KIT (PubMed:12878163). Interacts with PEAK3; the interaction requires PEAK3 homodimerization (PubMed:31311869). Translocated to the plasma membrane upon cell adhesion. The C-terminal SH3 domain function as a negative modulator for transformation and the N-terminal SH3 domain appears to function as a positive regulator for transformation. The SH2 domain mediates interaction with tyrosine phosphorylated proteins. Mediates interaction with SHB. Phosphorylated on Tyr-221 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-221 with the SH2 domain. This leads finally to the down-regulation of the Crk signaling pathway (PubMed:17515907). Isoform Crk-II: Phosphorylated by KIT (By similarity). Proline isomerization at Pro-237 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.