CK-9 is an alias for the gene, Keratin 9, type I, in humans. Other names include: Keratin, type I cytoskeletal 9; Cytokeratin-9; Keratin-9; cytokeratin 9; type I cytoskeletal 9; epidermolytic palmoplantar keratoderma; EPPK; K9. The encoded protein has an amino acid length of 623 and a mass of 62.1 kDa. CK-9 is a member of the Intermediate filament family. This gene shares homology with other species, including: Mouse.