a type I cytoskeletal keratin. The keratins are intermediate filament proteins responsible for the structural integrity of epithelial cells and are subdivided into cytokeratins and hair keratins. Keratin 18 and its filament partner keratin 8 are perhaps the most commonly found members of the intermediate filament gene family. They are expressed in single layer epithelial tissues of the body. Defects are a cause of cryptogenic cirrhosis. Note: This description may include information from UniProtKB.