As compared to continuous hypoxia (0.5–1% O2, 3 h), cycling hypoxia (0.5–1% O2, 1 h hypoxia, 30 min reoxygenation, 3 cycles) can induce chemoresistance against telozolomide in glioblastoma multiforme cells, U251, U87, and GBM8401 by inducing ROS formation which resulted into HIF-1α and NF-κB activation [60]. Here, NFKB1 is linked to glioblastoma.