A single bleomycin challenge was used to induce pulmonary fibrosis in WT and Fbln1c^–/– mice that were assessed 28 days later. Controls received PBS. (A) Tgfb mRNA levels in lungs were measured using qRT-PCR (n = 6). (B) LTBP1 levels in whole lung tissues were measured using immunoblot (left), and fold change was quantified using densitometry with normalization to β-actin (right, n = 6). Primary lung fibroblasts were isolated from whole lung tissues of naive WT and Fbln1c^–/– mice and stimulated with TGF-β or control medium. (C) p-Smad3 protein levels in fibroblast lysates were measured using immunoblot (left), and fold change was quantified using densitometry with normalization to vinculin (right, n = 6). (D) Fibroblasts were stained with β-actin, and myofibroblasts were stained with α-SMA (left), and the percentage of myofibroblasts as a percentage of total fibroblasts was determined (right; scale bar: 500 μm; n = 6). (E) Col1a1 mRNA levels in fibroblast lysates were measured using qRT-PCR (n = 6). (F) Col1a1 protein levels in fibroblast lysates were measured using immunoblot, and fold change was quantified using densitometry with normalization to β-actin (right, n = 6). Primary mouse lung fibroblasts from WT mice were incubated with bronchoalveolar lavage fluid (BALF, 20 μL each mouse, 120 μL total) from WT and Fbln1c^–/– mice after 28 days of bleomycin challenge and PBS controls for 6 hours. (G) Col1a1 and p-Smad3 protein in fibroblast lysates were measured using immunoblot, and (H) fold change was quantified using densitometry with normalization to vinculin (right, n = 6). Statistical differences were determined with 1-way ANOVA followed by Bonferroni’s posttest. *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001 compared with WT fibroblast controls. ^†P < 0.05, and ^††P < 0.01 compared with TGF-β–stimulated WT fibroblast controls.