Cytokeratin LMW (8/18) antibody [5D3] recognizes Cytokeratins (CK) 8 and 18 intermediate filament proteins. In normal tissues, [5D3] recognizes all simple and glandular epithelium. In neoplastic tissues, [5D3] may prove useful to aid in the identification of adenocarcinomas and some squamous cell carcinomas. It is generally negative in keratinizing squamous carcinomas. Studies suggest [5D3] can be used in conjunction with HMW CK to rule out squamous cell carcinoma. Studies have also shown CK 8/18 expression in squamous cell carcinomas of the oral cavity may indicate a decreased survival rate.