(A) Fbln1c deposition in lung sections from the nonfibrotic area and fibrotic area in patients with IPF and from healthy lung controls stained using immunohistochemistry (left); scale bar: 200 μm. Fbln1c-stained areas were quantified with normalization to the total area (right, n = 7–8). A single bleomycin challenge was used to induce pulmonary fibrosis in WT and Fbln1c^–/– mice. Controls were challenged with PBS. ^#P < 0.05, compared to nonfibrotic IPF. (B) Stained areas of total Fbln1 were quantified around small airways with normalization to the perimeter of the basement membrane (Pbm) (n = 6–8). (C) Fbln1 protein levels were assessed using immunoblot of whole lung tissues (left), and fold change of densitometry was normalized to β-actin and quantified (right, n = 8). (D) Twenty-eight days after bleomycin or PBS challenge, lung sections were assessed for protein of the 1c isoform, Fbln1c, around small airways using immunofluorescence (top); scale bar: 50 μm. (Insets show expanded images of indicated regions; scale bar: 15 μm.) Fbln1c-stained areas around airways were quantified with normalization to the Pbm (bottom, n = 8). (E) Fbln1c protein area in parenchyma was determined using immunofluorescence (left); scale bar: 50 μm. Fbln1c-stained areas were quantified with normalization to total area (right, n = 8). (F) Fbln1c protein levels were assessed in whole lungs using immunoblot (top), and fold change of densitometry was quantified with normalization to β-actin (bottom, n = 8). Statistical differences were determined with 2-tailed Student’s t test. *P < 0.05, **P < 0.01, and ***P < 0.001 compared with human healthy lung controls or PBS-challenged mouse controls.