As an immediate early gene, c-Myc is induced earlier than p53 mRNA accumulation17, 27 and its mRNA level parallels with p53 mRNA level in cell lines.14, 28 Ectopic c-Myc or N-Myc was able to trans-activate reporters driven by an E-box from the p53 promoter in 3T3 and neuroblastoma cells.17, 29 In an effort to decipher the requirements of p53 expression in vivo, we found the E-box element in the p53 promoter and its binding by c-Myc contributed significantly to high-level expression of p53 reporters in the proliferating compartments. Here, MYCN is linked to neuroblastoma.