SRC phosphorylates PTK2 (FAK1) at tyrosine residues Y576 and Y577 in the activation loop of PTK2. Phosphorylation of PTK2 at Y576 and Y577 is required for the full catalytic activity of PTK2 (Calelb et al. 1995, Lietha et al. 2007) and is facilitated by MET-mediated phosphorylation of PTK2 at Y194. MET is able to phosphorylate PTK2 at Y576 and Y577 in vitro, in the absence of SRC (Chen et al. 2011).