FOXO1 and glioblastoma: Since strong reduction in stem cell marker expression occurred only in FoxO1/3a double-deficient GBM-SCs (see Figures 5A, 5F, left, and S4) and FoxO3a appears more important than FoxO1 in normal NSCs [38, 39], we assessed the binding of both FoxO1 and FoxO3a to the sox2 regulatory region in GBM-SCs.