Hydrogen peroxide (H2O2) is a well-known antiseptic used in our homes since the 1920s. But did you know that our cells produce this molecule and that at low concentrations H2O2 instructs our cells to do different things, acting as a signaling molecule? In fact, H2O2 may oxidize several cellular components including proteins, altering their function. Healthy cells use H2O2 to regulate several of their behaviors, including proliferation, migration, or even cell-to-cell communication.