6B10 recognizes keratin K4 in non-cornifying squamous epithelia. Keratin K4 is mostly present in combination with keratin K13. In contrast to keratin K13, the superficial cells of the cornea are reactive with keratin K4. 6B10 also stains ciliated pseudo-stratified epithelium of bronchi and, focally, ductal epithelial cells. Polypeptide reacting: 59 kD keratin K4 (formerly also designated cytokeratin 4).
Positive control: squamous cell carcinomas