In our previous ischemic kidney injury study, after Nutlin‐3a treatment, neither MDM2 nor phospho‐MDM2 was changed at the kidney injury phase.12 Thus, we considered that Nutlin‐3a acts as a cofactor for NFκB at target gene promoters without changing MDM2 expression.2, 12 In addition, MDM2 directly activates NFκB p65 mRNA transcription by interacting with Sp‐1 biding site in the p65 gene promoter region in leukemia cells.25 We, therefore, speculate that DS‐5272 inhibits NFκB p65 transcription not by degrading MDM2 protein, but by inactivating NFκB transcription. This evidence concerns the gene SP1 and leukemia.