May be involved in neuronal differentiation. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with CDK5. Predominantly perinuclear. Expressed in brain. Up-regulated during apoptosis. Autophosphorylated. Phosphorylated by CDK5. Belongs to the protein kinase superfamily. Tyr protein kinase family.