Phosphorylation of Tyr397 in FAK triggers the phosphorylation of other tyrosine residues (Tyr407, Tyr576, Tyr577, Tyr861 and Tyr925) in a Src-dependent manner. The initial phosphorylation of FAK at Tyr397 is thought to create a high-affinity binding site for SH2 domains, enabling formation of a signalling complex between FAK and members of the Src-family kinases. Tyr-576 and Tyr-577 are located in the central catalytic domain and their phosphorylation is required for the maximum kinase activity of FAK. The tyrosine phosphorylation of these residues is likely to be mediated by Src (or other members of the src family).