Fig. 2.

Schema of mechanism with involvement of ROS-related factors to take place in mitochondria in temozolomide (TMZ) resistance. Toxicity of TMZ induces excessive superoxide generation which requires activation of ROS scavengers to detoxify. Accumulation of ROS, on the other hand, promotes tumorigenesis. The two-handed sword effect of ROS induced by TMZ can end up in sparing the intractable cells that have superior regulatory ability. The remaining cells that survive chemotherapy will thus thaw and replace the vulnerable counterparts. Cat catalase, GR glutathione reductase, GSH glutathione, GSSG glutathione disulfide