HIFs(HIF-1α and HIF-2α) in the hypoxic niche are upregulated via the expression of HIF-1α and HIF-2α isoforms in GBM and the roles of both HIF-1α and HIF-2α seem to be overlapping with 75% homologies between HIF-1α and HIF-2α (118). This evidence concerns the gene EPAS1 and glioblastoma.