MDM2 and pineal body neoplasm: Indeed, treatment of explanted pineal tumor cells with nutlin, a small-molecule inhibitor of the p53-mdm2 interaction (40), resulted in effective cell cycle exit and apoptosis upon p53 restoration by 4OHT treatment (Fig. 7G and H), proving the importance of the p53-Mdm2 interaction in abrogating p53 activity in this setting.