This MAb recognizes a protein of 58kDa, which is identified as Cytokeratin 5 (KRT5). This type II cytokeratin is specifically expressed in the basal layer of the epidermis with family member KRT14. Antibodies to KRT5 identify basal cells of squamous and glandular epithelia, myoepithelia, and mesothelium.Anti-cytokeratin 5 has been reported useful in the differential diagnosis of metastatic carcinoma in the pleura versus epithelioid mesothelioma. Almost all squamous cell carcinomas, half of transitional carcinomas, and many undifferentiated large cell carcinomas express.Anti-KRT5, along with anti-p63, affords a high sensitivity and specificity for squamous differentiation. Myoepithelial cells of the breast, glandular epithelia, and basal cells of the prostate are labeled with anti-KRT5.