To date several mechanisms for cytoplasmic sequestration of p53 in neuroblastoma have been proposed, including masking of the p53 C-terminal nuclear localization signal (Ostermeyer et al., 1996), hyperactive nuclear export (Stommel et al., 1999), binding to the cytoplasmic anchor, Parc (Nikolaev and Gu, 2003; Nikolaev et al., 2003), aberrant hyperubiquitylation of p53 (Becker et al., 2007), and MDMX and MDM2-mediated cytoplasmic tethering (Ohtsubo et al., 2009). This evidence concerns the gene MDM2 and neuroblastoma.