TP53 and neuroblastoma: MDM2 antagonists function through activation of p53 and hence efficacy of this therapeutic class is restricted to tumors that retain wild-type TP53. Mutations in TP53 occur rarely in neuroblastoma (Tweddle et al., 2003), and p53 pathway is mainly inactivated through mechanisms that affect stability and nuclear shuttling of p53 protein, such as MDM2 amplification and p14ARF impairment (Carr-Wilkinson et al., 2010).