LYN and cancer: Notably, gene expression profiling studies with a large set of breast tumors or cancer cell lines have identified basal epithelial types of tumors or cells that highly express CK5, EGFR and SFK LYN [24,25], which suggests that basal epithelial cells, as well as SFK and their cooperating partners, such as EGFR, have important roles in breast tumorigenesis [12].