PDK1 and melanoma: To test this hypothesis, we designed a biotin-labeled double-stranded DNA probe that contained the sequence of the −875 ∼ +40 region of the PDK1 gene promoter (Fig. 5A), and incubated it with the nuclear proteins from human immortalized fibroblasts (F), immortalized skin cells (SK) and five different melanoma cell lines (WM35, MEWO, Sk-mel-28, A375 and A431).