These results indicate that severe hypoxia at 1% O2 increases CD44, resulting in promotion of higher migration and invasion of GSCs, whereas moderate hypoxia at 5% O2 increases xCT expression, resulting in accumulation of extracellular Glu, leading to promotion of postoperative epileptogenicity in GBM as well as tumor proliferation (Figure 6). This evidence concerns the gene SLC7A11 and glioblastoma.