NR4A2 and neoplasm: When cells overexpressing NR4A2 were subjected to prolonged treatment with Nutlin-3a, we observed a substantial rescue of cells from Nutlin-3a–induced inhibition of proliferation (Fig. 6), suggesting that the inhibitory effect of NR4A2 on p53 activation is responsible for phenotypic observations that are indicative of p53-induced tumor suppression.