Patients with SSc exhibit increased expression of PDGF receptor subunits, PDGFRα and PDGFRβ, on cells in the skin and bronchoalveolar lavage (BAL) fluid, and have circulating autoantibodies that trigger PDGFR-mediated fibroblast activation and reactive oxygen species synthesis [45,46,47]. The gene discussed is PDGFRB; the disease is systemic sclerosis.