EPO and neuroblastoma: As the microarray data indicate upregulation of EPO by HIF-3α2 overexpression (Fig. 1a), and as we have previously shown that siRNA knockdown of all HIF3A splice variants results in downregulation of EPO mRNA by 39–60% and protein by 28–73% in Hep3B cells [12], we carried out further HIF-3α2 overexpression experiments in Hep3B and the EPO-producing SK-N-AS neuroblastoma cells, as well as siHIF3A knockdown experiments in the SK-N-AS cells.