May be involved in cell adhesion processes, particularly in the central nervous system. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Detected in brain, spinal cord, intestine, lung, stomach, ovary, testis, skin and eye. Levels are high at cleavage and blastula stage, and low at gastrulation stage. Subsequently, levels increase from mid-neurulation to the tail bud stage. Detected in embryonic brain at the tail bud stage. Tyrosine phosphorylated upon receptor stimulation. Belongs to the protein kinase superfamily. Tyr protein kinase family. AXL/UFO subfamily.