Reactive oxygen species (ROS) such as superoxide anions and hydrogen peroxide appear
to be transiently produced in response to growth factor and cytokine stimulation. A variety of
evidence suggests that this ligand‐stimulated change in the cellular redox state participates
in downstream signal transduction. This review will focus on the effects of ROS on signal
transduction pathways, the molecules that regulate intracellular ROS production and the
potential protein targets of oxidants.