Both p38 and PI3Ks control ROS generation in neutrophils.32,33 Whereas ROS can be generated by various sources, including the electron transport chain in mitochondria, xanthine oxydase, lipoxygenases, myeloperoxidases, and cyclooxygenases, professional phagocytes such as neutrophils and macrophages exhibit highly efficient ROS production by activation of their NADPH oxidase.