Non-receptor protein-tyrosine kinase implicated in signaling pathways involved in cell motility, proliferation and apoptosis. Activated by tyrosine-phosphorylation in response to either integrin clustering induced by cell adhesion or antibody cross-linking, or via G-protein coupled receptor (GPCR) occupancy by ligands such as bombesin or lysophosphatidic acid, or via LDL receptor occupancy. Microtubule-induced dephosphorylation at Tyr-397 is crucial for the induction of focal adhesion disassembly (By similarity). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Constituent of focal adhesions. Present in the fertilized egg and in cleavage and blastula stage embryos. During gastrulation, expression increases significantly and is detected in mesoderm, marginal zone ectoderm, and cells of the blastocoel roof. Later in development, prominently expressed at intersomitic junctions, in the brain and in several cranial nerves. Phosphorylated on tyrosine residues; phosphorylated kinase is first detected during gastrulation, suggesting that tyrosine phosphorylation is developmentally regulated. Belongs to the protein kinase superfamily. Tyr protein kinase family. FAK subfamily.