This protein encoded is a cytoplasmic nonreceptor protein kinase which may function as an intracellular signal transducer in epithelial tissues. Overexpression of this gene in mammary epithelial cells leads to sensitization of the cells to epidermal growth factor and results in a partially transformed phenotype. Expression of this gene has been detected at low levels in some breast tumors but not in normal breast tissue. Its presence in the nucleus appears to be linked to suppression of tumor progression. The encoded protein has been shown to undergo autophosphorylation.