MTOR and systemic sclerosis: Recently, Svegliati et al. demonstrated that PDGF and anti-PDGFR autoantibodies, which are elevated in SSc patient serum [40,41], stimulated higher growth rate, migration, and expression of collagen in human pulmonary artery smooth muscle cells, which was attributed to the generation of reactive oxygen species, and elevated NOX4 and mammalian target of rapamycin (mTOR) [42].