Inhibits the p53-Mdm2 interaction (Ki = 83 nM) and also dose-dependently reduces activation of the NF-κB pathway; prevents phosphorylation of IκBα by IKKα, IKKβ, and IKKE (IC50s = 80.5, 78.2, and 57.1 µM, respectively); inhibits the growth of A549 cell xenografts in mice.