HDAC6 and melanoma: The higher expression of HDAC6 in three melanoma cell lines (A375.S2, SK-MEL-28 and HT-144), compared with a normal skin epithelium cell line (HaCaT) or compared with normal human epidermal melanocytes (PIG1), was examined (Fig. 1C and D, **P < 0.01 and ***P < 0.001, respectively).