Furthermore, it is particularly well adapted for NB, a tumour originating from neural crest cells during embryonic development, by mimicking its pathophysiological conditions.24 This was confirmed by the fact that the tumourigenesis observed (Figure 1 and Supplementary Figure S1) was similar to the clinical phenotype, including haemorrhagic tumours18 and metastasis in similar organs.8, 19 Tumourigenesis occurred frequently for both MYCN-amplified and -non-amplified NB cell lines, whereas spontaneous metastasis only occurred for cells precultured in hypoxia. The gene discussed is MYCN; the disease is neoplasm.