Dihydroethidium (hydroethidine or DHE) is a widely used ethidium-based, redox-sensitive fluorescent probe. DHE has been shown to be oxidized by superoxide to form 2-hydroxyethidium (2-OH-E+) (ex 500-530 nm/em 590-620 nm) or by non-specific oxidation by other sources of ROS to form ethidium (E+) (ex 480 nm/em 576 nm).{32281,32282} Given their narrow spectral range, distinguishing between the two species using filter-based optical systems is often difficult and can lead to misreporting of the species of ROS being generated. This assay kit uses DHE as a fluorescent probe for the detection of ROS generation. Antimycin A, an inhibitor of complex III of the mitochondrial electron transport chain, is included as a positive control for ROS generation. N-acetyl Cysteine is included as an antioxidant control.