The keratins are the typical intermediate filament proteins of epithelia, showing an outstanding degree of molecular diversity. Heteropolymeric filaments are formed by pairing of type I and type II molecules. In humans 54 functional keratin genes exist. They are expressed in highly specific patterns related to the epithelial type and stage of cellular differentiation. This antibody can detect high molecular weight CK10, CK14, CK15 and CK16 and low molecular weight CK19. It usually used in a cytokeratin cocktail with type II cytokeratin antibody.