Localization and expression of Prx II, PDGF receptors (PDGFRa, PDGFRb), Ki67 (a marker of cell proliferation), and nitrotyrosine (a marker of oxidative-nitrosative stress) were assessed in ten IPF/UIP lung biopsies and ten controls by immunohistochemistry and morphometry. The gene discussed is PDGFRB; the disease is idiopathic pulmonary fibrosis.