The keratins are intermediate filament proteins responsible for the structural integrity of epithelial cells. KRT19,one of type I keratins,is specifically expressed in the periderm,the transiently superficial layer that envelopes the developing epidermis. Due to its high sensitivity,KRT19 is the most used marker for detection of tumor cells disseminated in lymph nodes,peripheral blood,and bone marrow of breast cancer patients. This antibody,generated against full length KRT19 protein,also recognizes KRT17,another type I keratin homologous to KRT19. KRT17 is used as a marker for trauma.