We found that the IC50s of RG7112 for malignant meningioma cells (IOMM-Lee) and normal fibroblasts (IMR90) were higher and lower, respectively, than those of CEP-1347 [47], which suggested that CEP-1347 may be superior to MDM2 antagonists as a therapeutic activator of p53 at least for meningiomas expressing MDM4, the presumed target of CEP-1347. This evidence concerns the gene TP53 and meningioma.