Involved in cell branching and adhesion mediated by BCAR1-CRK-RAPGEF1 signaling and activation of RAP1. 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 (By similarity). May regulate the EFNA5-EPHA3 signaling (PubMed:11870224). Component of a complex comprised of SH2D3C, BCAR1/CAS, and CRK (By similarity). Within the complex, interacts with SH2D3C (via C-terminus), and BCAR1/CAS (By similarity). Found in a complex with ABL1, ABL2, CRK and UNC119; leading to the inhibition of CRK phosphorylation by ABL kinases (By similarity). 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. Interacts with FLT4 (tyrosine-phosphorylated). 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 (By similarity). Interacts (via SH2 domain) with PDGFRA (tyrosine phosphorylated) and PDGFRB (tyrosine phosphorylated) (By similarity). 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 (By similarity). Translocated to the plasma membrane upon cell adhesion. Ubiquitous. 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:8194526, PubMed:12878163). 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.