TP53 and neoplasm: Consistent with observations that Mdm2 haploinsufficiency inhibits c-MYC induced lymphomagenesis (Alt et al., 2003), MDM2 has been shown to be necessary for MYCN to overcome p53-mediated tumor suppression for MYCN directed centrosome amplification and genomic instability (Slack et al., 2007), and also during MYCN driven neuroblastoma tumorigenesis (Chen et al., 2009; Figure 2).