TP53 and neuroblastoma: Anaplastic lymphoma kinase (ALK) is another transcriptional target of MYCN, and ALK triggers MYCN transcription in neuroblastoma cell lines, which generates a positive feedback loop.121, 122, 123 Mechanistically, ALK drives MYCN expression by activating the p53 promoter via extracellular signal-regulated protein kinase 5124 (Fig. 3D).