Control of ACAD by ROS. TCR activation leads to increased mitochondrial production of superoxide that is converted to H₂O₂ either via reactions with endogenous substrates (not shown) or via manganese superoxide dismutase (MnSOD). These ROS may have effects on various transcription factors, such as CREB, that may play a role in the downregulation of Bcl-2 and in subsequent sensitivity of T cells to the effects of ACAD.