MYCN and neuroblastoma: However, considering the following facts (i) the mutation of p53 is rare in primary NBs; (ii) p53 is induced and p53-dependent apoptotic pathway is activated in response to chemotherapeutic agents in NB murine models [56] as well as NB cell lines, and (iii) exogenous expression of TrkA induces p53-mediated apoptosis even in the NB cells with MYCN amplification, which is inhibited by p53 inactivation [57], p53 should be of functional importance and contribute to apoptotic cell death in favorable NB.