Although hypoxia-inducible erythropoietin (EPO) gene expression was shown in human neuroblastoma cells (56), downregulation of Epo mRNA was found in LuM1 aggregates as compared with Colon26 cells, We next examined whether ABCG1 depletion altered HIF-1α levels in tumors. This evidence concerns the gene ABCG1 and neuroblastoma.