Figure 2.

How cells respond to oxidative stress. Adapted from Halliwell and Gutteridge (2006) by courtesy of Oxford University Press. Stimulation of proliferation by low levels of reactive species is associated with increased net phosphorylation of multiple proteins. The cell is generally a reducing environment, especially the mitochondria (GSH/GSSG > 100) and cytosol (GSH/GSSG > 100), but less so in the endoplasmic reticulum (ER) lumen (GSH/GSSG = approximately 3), since a more-oxidizing environment is required for optimal protein folding and disulphide bridge formation. HO-1, Haem oxygenase 1; RS, reactive species.