Keratin 14 is a member of the type I keratin family of intermediate filament proteins. Keratin 14 was the first type I keratin sequence determined. Keratin 14 is also known as cytokeratin-14 (CK-14) or keratin-14 (KRT14). In humans it is encoded by the KRT14 gene. Keratin 14 is expressed in mitotically active basal layer cells, along with its partner keratin 5 (K5), and their expression is down-regulated as cells differentiate. Keratin 14 has been studied as a prognostic marker in breast cancer. Keratin 14 distinguishes stratified epithelial cells from simple epithelial cells and has been reported useful in the identification of squamous cell carcinomas.