Fig. 8.

Overwhelming of antioxidative defenses leads to induction of defense mechanisms. Since the constant formation of reactive species is an inevitable by-product of life, mammalian cells are endowed with a remarkable asset of antioxidative systems. In case of an increase of ROS to above “normal” (physiological) level, an antioxidative response will be induced. The central redox-sensor Keap1/Nrf2 becomes activated and induces the expression of a variety of antioxidative (NQO1: NAD(P)H quinone dehydrogenase 1; GST: glutathione S-transferase; Gpx2: glutathione peroxidase 2; HO-1: heme oxygenase-1; Txnrd1: thioredoxin reductase 1; Srx: sulfiredoxin; SOD: superoxide dismutase; Cat: catalase; Nrf2: nuclear factor erythroid 2-related factor 2), anti-inflammatory (iNOS: inducible nitric oxide synthase; COX2: cyclooxygenase-2) and detoxifying enzymes (GCL: glutamate cysteine ligase), as well as parts of the ubiquitin-proteasome-system (UPS). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article).