We also performed immunofluorescence analysis for nuclear localization of NOTCH (NICD) and found that PLK1 knockdown melanoma cells showed significantly decreased NICD levels in the nucleus (Fig. 6c), while only PLK1 overexpressing A375 cells and constitutively active PLK1 (T210D) containing SK-MEL-2 melanoma cells showed increased levels of NICD in the nucleus (Fig. 6d). This evidence concerns the gene NOTCH1 and melanoma.