TP53 and cancer: Similarly, agents that activate the p53 tumour-suppression pathway, including Nutlin and HLI98, small molecules that block the p53-Mdm2 interaction (Vassilev et al, 2004), and inhibit the E3 ubiquitin ligase activity of Mdm2, respectively, (Yang et al, 2005) are currently being tested for their potential use in cancer therapy.