Nutlin-3, a tetra-substituted imidazoline, is a potent and selective small-molecule antagonist of murine double minute 2 (MDM2), which occupies the binding site of p53 in MDM2 and consequently prevent MDM2 binding to p53 leading to the disruption of the autoregulator feedback loop and the fostering of the p53 tumor suppressor network. It also binds to murine double minute 4 (MDM4), which is another component of the p35 tumor surveillance pathway. Nutlin-3 is being investigated as an antitumor agent for its antiangiogenic activity in cells through inhibiting endothelial cell migration, inducing cell cycle arrest, and increasing apoptotic tendency in endothelial cells.