TP53 and acute lymphoblastic leukemia: Gu et al. (2008) instead showed a cytotoxic activity of Nutlin-3a, a cis-imidazoline small molecules antagonizing Mdm2-p53 binding, in pediatric ALL with p53 wild-type and over-expressing MDM2. Moreover, they also found the positive correlation between MDM2 expression and Nutlin-3A cytotoxicity in ALL. In fact, a major effect of Nutlin was observed in cells over-expressing MDM2 respect to MDM2-negative ALL cells, probably due to the higher induction of p53, p21, Bax, and PUMA (Gu et al., 2008).