Production of ROS plays a role in signaling by TGF-β and PDGF (5, 7, 31–33), 2 key profibrotic factors in SSc, and higher levels of ROS have been reported in SSc fibroblasts and in tissues and fluids from patients with SSc (7, 34, 35). This evidence concerns the gene TGFB1 and systemic sclerosis.