Figure 1
From: Oxidative stress responses - what have genome-scale studies taught us?
Oxidative stress results from imbalance between the levels of reactive oxygen species (ROS) and antioxidants (AOX). Under normal circumstances, cells are able to balance the production of oxidants and antioxidants (such as catalase and superoxide dismutase), resulting in redox equilibrium. Oxidative stress occurs when cells are subjected to excess levels of ROS, or as a result of depletion in antioxidant defenses.