In addition, SOX2+ (or NANOG+) HIF-1α+ RNApII-S2P-/low cells were not observed in grade II–III astrocytomas that lacked necrosis according to their diagnostic criteria, indicating that this subpopulation of tumor cells is specific to glioblastoma (Fig 3E–3G). This evidence concerns the gene SOX2 and glioblastoma.