P130CAS (CRK-associated substrate/BCAR1) contains multiple protein-protein interaction domains including an N-terminal SH3 domain, an interior substrate domain (SD), a Src-binding domain (SBD) near the C-terminus and a conserved C-terminal Cas-family homology (CCH) domain. The SH3 and CCH domains mediate localization to focal adhesions (FAs) while SD and SBD are involved in initiating signaling events (Meenderink et al. 2010, Shin et al. 2004). The BCAR1 SD undergoes tyrosine phosphorylation and mediates signals by recruiting downstream effectors. The SD is characterised by fifteen YxxP motifs, of which ten can be efficiently phosphorylated by Src family kinases (SFKs) (Shin et al. 2004). PTK2/FAK kinase phosphorylates the nearby SBD tyrosines 664 and 666 (mouse 668/670). These SBD tyrosines provide the additional binding sites for Src-SH2 domains, stabilizing the SRC-BCAR1 association (Ruest et al. 2001). Note: Phosphorylated tyrosine numbering in human BCAR1 is based on similarity with the mouse p130Cas.