Figure 3. Fibrosis is not altered in bleomycin-treated Cav-2^−/− mice. (A) The collagen content is similar in lungs of bleomycin-treated wild-type and Cav-2^−/− mice. Hydroxyproline content of the right lung was determined and expressed as the total amount per lobe (upper panel) and as a percentage of the hydroxyproline content in saline-treated mice (lower panel) (**P < 0.01, n = 5–7 for each group). (B) The expression and activation of members of the TGF-β signaling pathway are not altered in Cav-2^−/− mice. Upper panel: TGF-β levels were determined in lysates from the right lung of mice instilled with saline or bleomycin for 14 d (*P < 0.05, ***P < 0.001, n = 5–9 for each group). Lower panel: Expressions of the TGF-β receptor I and the phosphorylated form of Smad2/3 were detected by immunoblot analyses of lung lysates from wild-type and Cav-2^−/− mice instilled intratracheally with saline or bleomycin and were shown to be present in similar levels in wild-type and Cav-2^−/− mice. β-actin is shown as a control for equal protein loading. Each group consists of 3–6 mice (WT SAL, n = 3; WT BLEO, n = 4; Cav-2^−/−, n = 6, and Cav-2^−/−, n = 5).