Figure 1. Schematic representation of the roles of oxidants and antioxidants in determining oxidative stress.

Through redox signaling, oxidants can directly upregulate antioxidant defense or indirectly ameliorate mitochondrial homeostasis, thus reducing oxidant production. Redox signaling also modulates cellular metabolic process and inflammation to minimize oxidants. Failure or discord of redox signaling leads to a tip of oxidant-antioxidant balance in favor of the former and thus oxidative stress. Arrow-headed lines represent activation; dot-ended lines represent inhibition.