KLF4 and glioma: In addition, hypoxia promotes glioma stem cell (GSC) formation by inducing stem cell marker genes, including octamer-binding transcription factor 4 (OCT4), NANOG, SRY-Box transcription factor 2 (SOX2), Kruppel-like factor 4 (KLF4), and cMYC, while downregulating expression of glial fibrillary acidic protein (GFAP) [92,93], and this was further shown to be critical for inducing radioresistance.