NADPH oxidase (Nox) isoforms are a family of enzymes that generate superoxide and hydrogen peroxide as primary oxidants during the activation of oxygen. Nox isoforms play a key role in immunity, infection, and inflammation. Yet, to date there are no inhibitors for the different Nox isoforms. This is largely due to the lack of availability of specific probes and assays for detecting reactive oxygen species (ROS) such as superoxide and hydrogen peroxide. In this seminar, I will discuss a medium throughput approach to detect specific inhibitors of Nox2 using a multitude of ROS probes and assays. In the second part of the talk, I will discuss a relatively new and non-toxic antitumor therapeutic strategy using the mitochondria-targeted drugs (metformin analogs, in particular).