Fig. 1
From: Reactive oxygen species: a volatile driver of field cancerization and metastasis
Fate of ROS: NOX proteins are integral membrane proteins of cells and release superoxides (O2•−) as products directly into the extracellular space. Functional NOX proteins can also be internalized into forming redoxosomes, producing superoxides (O2•−) within the redoxosomes. Furthermore, from cells such as macrophages, exosomal NOX complexes can be released and being incorporated into surrounding cells via endocytosis. Besides NOX, xanthine oxidase and nitric oxide synthase proteins (both not shown) can also generate extracellular and intracellular superoxides (O2•−) respectively. Superoxides (O2•−) are relatively impermeable through the cell membrane. However, intracellular and extracellular SOD proteins catalyze the dismutation of superoxides (O2•−) into H2O2 and O2. H2O2 molecules are relatively permeable through the aquaporins of the cell membrane and hence, can travel easily from cell to cell, providing regional oxidative stress