This antibody labels the cytokeratin 18 (CK18) protein. It reacts with a wide variety of neoplastic tissues such as gastrointestinal tract, lung, and breast tumors. It does not react with tumor cells of nonepithelial origin such as glioma, melanoma and osteosarcoma. It also does not react with stratified squamous epithelium on most squamous cell carcinomas. This antibody may be useful when used in a panel of antibodies.