Ks 7.18 represents an excellent marker for the discrimination of specific subtypes of adenocarcinoma: e.g. adenocarcinoma of pancreas, bile duct carcinoma and transitional carcinoma of bladder are stained, whereas hepatocellular and prostate carcinomas are negative. Detects specific subtypes of adenocarcinomas: Adenocarcimona of pancreas, gallbladder, lung, cervix; cholangio carcinoma of liver; ductal and lobular carcinoma of breast; carcinomas of ovary; transitional cell carcinoma of bladder; mesothelioma; negative with most cases of hepatocellular carcinoma. In colorectal carcinoma early stages are reported to be negative but advanced stages of tumor development are positive for keratin K7 expression. Occasionally, staining of blood vessel walls, particularly of endothelial cells may be observed. Reacts with Mr 54,000 polypeptide (keratin K7; formerly also designated cytokeratin 7) of human glandular epithelia. Reactivity on cultured cell lines: HeLa, RT 112, T24, BT-20, CAMA-1, Detroit 562, (MCF-7, HT-29, are negative)