In an attempt to clarify this rather complex in vivo effect of HIF2α on neuroblastoma growth, we removed tumours at days 19 (just before the growth acceleration of HIF2α nodules) and 28 for controls and HIF2α(1–485) cells and at days 19, 28 and 35 for HIF2α nodules. The gene discussed is EPAS1; the disease is neuroblastoma.