RB1 and melanoma: RB1 downregulation by RNA interference led to vemurafenib resistance in A375 and SKMEL-5 cell lines, increasing proliferation rate (Figure 7E) and no significant variation in proliferation rate was observed with cyclosporin (immunosuppressant reported to inhibit melanoma cell proliferation [22]), suggesting the implication of RB1 in mediating vemurafenib resistance (Supplementary Figure 5).