Pan Cytokeratin antibody Plus is a combination of [AE1/AE3] and Cytokeratin (CK) 8/18 [5D3] and can be used to detect most human epithelia. [AE1/AE3] recognizes acidic and basic subfamilies of cytokeratins, with molecular weights ranging from 40 to 67 kDa. CK8/18 [5D3] recognizes Cytokeratin 8 and 18 intermediate filament proteins. In normal tissues, [5D3] recognizes all simple and glandular epithelium. It has been observed that [AE1/AE3] has had problems marking certain tissues types and adenocarcinomas. The addition of CK 8/18 may remedy some of the limitations observed when staining with [AE1/AE3] alone.