MDM4 and cancer: In the course of developing therapeutic strategies to disrupt the interaction between p53 and MDM2/MDMX, 4,5-dihydroimidazoline (Nutlin; Roche) was the first small molecule compound identified to specifically disrupt the p53–MDM2 interface and thus increase p53 stability and activity, leading to cell-cycle arrest, apoptosis, senescence, and differentiation of cancer cells [15,16].