The reduction in melanoma clonogenic cell survival by MDM2 antagonists was potentiated by GSK2830371 (WIP1i). (A) The p53-wild-type (WT) melanoma cell lines (A375, WM35 and C8161) were treated by different concentrations of MDM2 antagonists (nutlin-3 or RG7388), combined with or without WIP1i (2.5 μM) for 72 h. (B) Summary of the effect of WIP1 inhibition on LC50 values for nutlin-3 or RG7388 from at least three independent repeats. (C) Clonogenic survival of p53WT and p53 MT cells treated with either DMSO, WIP1i, nutlin-3, RG7388 or combination. (D) Clonogenic formation of C8161 cells following treatment with nutlin-3 (200 nM), RG7388 (20 nM), WIP1i (2.5 μM) or combination. *P<0.05, **P<0.005, ***P<0.0005.