Figure 2.

Putative mechanisms for ROS-mediated activation of MAPK pathways. ROS are activated by growth factors, cytokines, and various stresses and rapidly removed by intracellular antioxidant proteins. ROS, once ROS production exceeds the capacity of the antioxidant proteins, may induce oxidative modification of MAPK signaling proteins (e.g., RTKs and MAP3Ks), thereby leading to MAPK activation. ROS may activate MAPK pathways via inhibition and/or degradation of MKPs.