MYCN and neoplasm: Taken together, analysis of Th‐MYCN, Alk‐F1178S;Th‐MYCN and Rosa26_Alkal2;Th‐MYCN mice revealed a high level of tumour penetrance in both Alk‐F1178S;Th‐MYCN (98% at 200 days) and Rosa26_Alkal2;Th‐MYCN (89% at 200 days), relative to that observed in Th‐MYCN mice (46% at 200 days; Fig 4F).