Cytokeratin 20 (CK20) with a molecular weight of 46 kDa, it is mainly expressed in gastrointestinal epithelium, urinary epithelium and Merkel cells. Cytokeratin 19 Monoclonal Antibody is mainly used in the judging of gastrointestinal adenocarcinoma, ovarian mucinous tumor and Merkel cell carcinoma. CK20 is not expressed in squamous cell carcinoma, breast cancer, lung cancer, endometrial cancer and non-mucinous ovarian cancer.