The increase of the expression of these two enzymes was reasonably induced by the enhanced expression of the transcriptional factors Sp1 (average increase: 100%, melanoma cells versus adult melanocytes; P < 0.001) (Figure 6C), as it was reported that both NEU3[42] and GD3 synthase gene promoters [43] are regulated by them. Here, NEU3 is linked to melanoma.