The increase in levels of active oxygen species or free radicals known as oxidative stress induces lesions that impair or kill cells and initiate disease and degenerative processes such as aging, carcinogenesis, and immunodeficiencies. Protective mechanisms have been uncovered in both eukaryotes and prokaryotes and are being vigorously studied at a molecular level, assisting the search for ways of reducing or avoiding oxidative stress. Written and edited by leaders in this growing field, this volume is an essential work of reference for specialists and investigators with wider interests in cell biology, aging, and cancer biology.