Cytokeratin-7 (CK-7) is a protein that in humans is encoded by the KRT7 gene. CK-7 is a type II keratin. CK-7 is found in simple glandular epithelia, and in transitional epithelium. Epithelial cells of the lung and breast both contain CK-7, but some other glandular epithelia, such as those of the colon and prostate, do not. Because the CK-7 antigen is found in both healthy and neoplastic cells, antibodies to CK7 can be used in immunohistochemistry to distinguish ovarian and transitional cell carcinomas from colonic and prostate cancers, respectively. It is commonly used together with CK20 when making such diagnoses.
