Cytokeratin 14 (CK14) is a 50-kDa keratin expressed in abundance in stratified epithelial cells, epidermal cells, basal cells, mesothelial cells, and myoepithelial cells in various tissues including breast and prostate. CK14 is helpful in the identification of breast cancer with basal phenotype. It has been reported that cytokeratin 5/14-positive breast cancers are true basal phenotype confined to BRCA1 tumors. Along with p63 and CK5, CK14 has been a useful marker for cells with basal, squamous and myoepithelial differentiation.