This MAb recognizes basic (Type II or HMW) cytokeratins, which include 67kDa (CK1); 64kDa (CK3); 59kDa (CK4); 58kDa (CK5); 56kDa (CK6); 52kDa (CK8). Twenty human keratins are resolved with two-dimensional gel electrophoresis into acidic (pI 6.0) subfamilies. The acidic keratins have molecular weights (MW) of 56.5, 55, 51, 50, 50 , 48, 46, 45, and 40kDa. MAb AE3 recognizes the 65-67, 64, 59, 58, 56, and 52kDa keratins of basic subfamily. Many studies have shown the usefulness of keratins as markers in cancer research and tumor diagnosis. AE1/AE3 is a broad spectrum anti pan-keratin antibody cocktail, which differentiates epithelial tumors from non-epithelial tumors e.g. squamous vs. adenocarcinoma of the lung, liver carcinoma, breast cancer, and esophageal cancer.