Non-receptor tyrosine-protein kinase that negatively regulates cell proliferation. Positively regulates PTEN protein stability through phosphorylation of PTEN on 'Tyr-336', which in turn prevents its ubiquitination and degradation, possibly by reducing its binding to NEDD4. May function as a tumor suppressor (By similarity). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Interacts (via the SH3-domain) with PTEN. Interacts with RB1 (By similarity). Predominantly found in the nucleus, with a small fraction found in the cell periphery. Expressed in intestinal tract, fetal and adult islets of Langerhans, kidney, liver and lung. Mice are viable and do not show any histological abnormalities in epithelial tissues or develop any pathological and/or metabolic disorders associated with the failure of epithelial organs. Belongs to the protein kinase superfamily. Tyr protein kinase family. SRC subfamily.