MYCN and neuroblastoma: Initial studies in neuroblastoma showed that MYCN amplified tumors expressed significantly higher levels of p53 mRNA in comparison with non-amplified tumors (Raschella et al., 1991; Berwanger et al., 2002; Westermann et al., 2008), and higher p53 protein expression in the presence of ectopic MYCN in cell lines (Cui et al., 2005; Bell et al., 2006; Sugihara et al., 2006).