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. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Interacts (via the SH3-domain) with PTEN. Interacts with RB1. Predominantly found in the nucleus, with a small fraction found in the cell periphery. Predominantly expressed in epithelial derived cell lines and tissues, especially normal liver, kidney, breast and colon. Belongs to the protein kinase superfamily. Tyr protein kinase family. SRC subfamily.