SOX2 and glioblastoma: In contrast, SOX2+ HIF-1α+ RNApII-S2P-/low cells could neither be detected around small necroses with pseudopalisading of tumor cells, which is another type of necrosis in glioblastoma tissues [1, 37, 38] (Fig 3A and 3B), nor in the areas devoid of necrosis (Fig 3C and 3D).