Anti-Keratin 4 antibodies are used in the immunodetection of the protein encoded by the KRT4 gene. In humans, the canonical protein has a reported length of 520 amino acid residues and a mass of 56.1 kDa. A member of the Intermediate filament protein family, it is known to be involved with cytoskeleton organization and epithelial cell differentiation. Other names for this target antigen include CK4, CYK4, K4, WSN1, keratin, type II cytoskeletal 4, cytokeratin 4, keratin 4, type II, and CK-4.