CHUK and epidermolytic palmoplantar keratoderma, 1: It is also noteworthy the differentially expressed genes found in HaCat- IKKα skin equivalents which are involved in the development of palmoplantar keratoderma, a heterogeneous group of disorders characterized by abnormal thickening of the palms and soles; being this phenotype consistent with the excesive differentiation displayed by the HaCat-IKKα skin equivalents.