USP7 and melanoma: Consistent with a reduction in ac-DNMT1 protein level during melanoma disease progression (Figure 3A,C), a significant decrease in USP7 protein levels were observed in stage III (mean H-score = 110, p = 0.0006) and stage IV metastasis (mean H-score = 140, p = 0.02) compared to normal organ tissues (mean H-score = 173, Figure 5E).