Our previous studies and others have demonstrated that MDM2 activates HIF-1α in a p53-independent manner, which leads to downstream vascular endothelial growth factor (VEGF) expression.20 Inhibition of MDM2 with the small-molecule inhibitor Nutlin-3a suppresses the HIF-1α/VEGF pathway and subsequent VEGF-mediated tumor angiogenesis in neuroblastoma.20 In the current study, we sought to determine the effect of RG7388, which belongs to a different class of molecules based on its pyrrolidine ring, on this angiogenesis pathway in neuroblastoma. This evidence concerns the gene TP53 and neuroblastoma.