Our previous studies have suggested that mitochondrial dysfunction causes oxidative genomic DNA damage and contributes to tumorigenesis. However, oxygen also serves as an essential factor for cellular bioenergetics. We are currently pursuing studies to modulate oxygen homeostasis to examine its effect on energy metabolism and tumorigenesis. Oxygen also profoundly affects cardiovascular function and diseases, so we are interested in examining the mechanisms by which oxygen homeostasis may affect atherosclerosis.