Keratin is a type I and type II intermediate filament protein that forms a cytoskeletal network in all epithelial cells. They are expressed in pairs in a tissue- and differentiation-specific manner. In recent years, a rare autosomal dominant genetic disease-white sponge nevus (WSN) in the oral mucosa is related to mutations in the keratin 4 (KRT4) and keratin 13 (KRT13) genes.
