Anti-cytokeratin clone ZM374 is a mixture of anti-cytokeratin antibodies reacting with all 20 subtypes of cytokeratins. Unlike pan-cytokeratin clone AE1/AE3, ZM374 reacts with CK7, CK8, CK18, and CK20. In normal tissues, ZM374 is reactive with most epithelial types, including bile ducts and hepatocytes in the liver, bladder epithelium, breast ducts, bronchial epithelium, endometrium, intestinal epithelium of the stomach, duodenum, ileum, colon, rectum, pancreas, ovarian epithelium, pancreatic acini, pituitary acini, pneumocytes, prostate, thyroid, skin (positive on the basal layer and negative on the superficial layers of squamous epithelium), and apocrine and sweat glands. In tumors, ZM374 is reactive with most carcinomas, including breast, transitional cell (TCC), renal cell (RCC), lung adenocarcinoma, lung small cell, lung squamous cell, endometrial, prostate, ovarian, hepatocellular (HCC), colorectal CA, stomach and thyroid. It is negative in certain normal tissues, including the brain, lymphocytes, and all cells of hematolymphoid origin, muscle, brain, nerves, endothelium, and in certain tumors including most melanomas, sarcomas, lymphomas, primitive neuroectodermal tumors (PNET)/Ewing’s and gastrointestinal stromal tumors (GIST). Positivity has been seen on some dendritic cells in lymph nodes, some endothelia, and some muscle cells.