MW 48,000 (pI 5.1) intermediate filament polypeptide, keratin K16, detected by immunohistochemistry in psoriatic skin, in the rete ridges of foot sole epidermis, in tongue, esophagus, exocervix and in squamous cell carcinoma of skin, tongue and cervix. In the hair follicle, staining was restricted to the outer root sheath. Completely non-reactive were cells of non-stratified epithelia (e.g. liver, colon).