Keratins (cytokeratins) are intermediate filament proteins that are mainly expressed in epithelial cells. Keratin heterodimers composed of an acidic keratin (or type I keratin, keratins 9 to 23) and a basic keratin (or type II keratin, keratins 1 to 8) assemble to form filaments. Keratin isoforms demonstrate tissue- and differentiation-specific profiles that make them useful as research biomarkers. Research studies have shown that mutations in keratin genes are associated with skin disorders, liver and pancreatic diseases, and inflammatory intestinal diseases.
Keratin 20 is primarily expressed in gastric and intestinal epithelium, urothelium, and Merkel cells. Research studies have shown that keratin 20 is an important marker of colon, liver, pancreatic, Merkel cell, and gastric cancer.