The NOX family of NADPH (nicotinamide adenine dinucleotide phosphate-oxidase) oxidases are transmembrane proteins that transfer electrons across biological membranes. The function of NOX enzymes is to generate reactive oxygen species (ROS) from oxygen.

ROS interact with other small inorganic molecules, proteins, lipids, carbohydrates and nucleic acids. These interactions have various physiological roles and form a part of normal cellular signalling. However, in various diseases, increased NOX enzyme activity leads to higher levels of ROS production, increasing the activity of disease-driving signalling pathways and also causing direct damage to tissues.