FIG. 2.

Sources of ROS and their effects in the mammalian cells. ROS have many sources, including ionizing radiation, oxidizing chemicals and enzymes, immune cells, and mitochondrial respiration. In the cell, increased levels of oxidative stress from excessive ROS can cause a variety of harmful effects to cellular components and biomolecules, including DNA damage, lipid peroxidation, protein oxidation, and enzyme degradation. ROS, reactive oxygen species. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/ars