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. Highly expressed in stomach, small intestine and colon. Concentrated in the brush border membranes of epithelial cells, throughout the maturation axis of the adult small intestine. Belongs to the protein kinase superfamily. Tyr protein kinase family. SRC subfamily.