SKP2 and melanoma: In line with these observations, we also found highly expressed Skp2 in Vem-resistant melanoma cells (Figures 1B, 2D), and decreased AKT expression and AKT phosphorylation in two single clones of VR1-SgSkp2 cells (VR1-SgSkp2-No.1 and No.2), which might be the reason to increased cell apoptosis and cell growth arrest caused by the combination regimen (Figures 2, 3C).