In addition to its well-known roles in the electron transport chain and cell apoptosis, according to a recent study cytochrome c can also act as an antioxidative enzyme in the mitochondria; it does so by removing superoxide (O) and hydrogen peroxide (HO) from mitochondria. Therefore, not only is cytochrome c required in the mitochondria for cellular respiration, but it is also needed in the mitochondria to limit the production of O and HO.