Src family kinases (SFKs) induce transphosphorylation of tyrosyl residues Y576, Y577, Y861 and Y925. Phosphorylation of Y576 and Y577 within the catalytic domain confers maximal FAK1 enzymatic activity and signaling in response to adhesion (Calalb et al. 1995, Brunton et al. 2005). Y576 and Y861 are both phosphorylated in a Src-dependent manner in response to VEGF (Abu-Ghazaleh et al. 2001, Le Boeuf et al. 2006, 2004). Phosphorylation of FAK on Y861 contributes to the recruitment of vinculin to FAK1 (Le Boeuf et al. 2004).