The BH3 mimetic and selective Mcl-1 inhibitor S63845, has shown convincing effects on cell viability in a large number of hematological cancer cell lines [27], whereas in melanoma cell lines, high sensitivity (IC50 < 1 μM) and significant effects on cell death, were reported in only a minority (14%) of cell lines [37]. This evidence concerns the gene MCL1 and melanoma.