May function in signaling pathways utilized broadly during fetal development and more selectively in adult tissues and in cells of the lymphohematopoietic system. Could specifically be involved in phospholipid signal transduction (By similarity). Involved in negative regulation of cell growth. Has tumor suppressor properties. Plays a negative regulatory role in the Ras-MAPK pathway. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Interacts with the SH3 domain of PLCG1 via its Pro-rich domain. Expressed in whole embryo and all adult tissues examined including liver, kidney, heart, brain, skeletal muscle and intestine. Also detected in various myeloid- and lymphoid-derived cell lines. Expression during embryogenesis increases between 7 dpc and 11 dpc. Levels of expression subsequently decrease and reach a steady-state level by 17 dpc. Autophosphorylated on tyrosine residues. Mice develop spontaneous tumors, including lymphomas and carcinomas at high rates. Belongs to the protein kinase superfamily. Tyr protein kinase family.