Tyrosine-protein kinase implicated in the control of cell growth. Plays a role in the regulation of intracellular calcium levels (By similarity). Required in brain development and mature brain function with important roles in the regulation of axon growth, axon guidance, and neurite extension. Blocks axon outgrowth and attraction induced by ntn1 by phosphorylating its receptor ddc. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Inhibited by phosphorylation of Tyr-531 by leukocyte common antigen and activated by dephosphorylation of this site. Associates through its SH3 domain, to the p85 subunit of phosphatidylinositol 3-kinase. Expressed in early tail-bud embryos at stage 20 in the brain region of the neural tube and at lower levels throughout the remaining length of the neural tube. Present at stage 32 in the forebrain, midbrain, the ventral half of the hindbrain and the spinal cord. Belongs to the protein kinase superfamily. Tyr protein kinase family. SRC subfamily.