Fig. 4.

αSMA-directed deletion of αv integrins does not confer protective effects against bleomycin-induced pulmonary fibrosis. A: schematic of either PDGFRβ-Cre- (12) or αSMA-driven Cre- (9, 37) mediated recombination of the floxed αv integrin, which leads to removal of exon 4, shift in the translational reading frame in subsequent exons, and permanent inactivation of αv integrin expression (25). B: immunoblotting of expression of αv integrins in cells targeted by PDGFRβ-Cre or αSMA-driven Cre. Mice were treated with bleomycin for 14 days, and tdTomato-positive cells were purified by fluorescence-activated cell sorting (FACS), followed by immunoblotting with anti-αv integrin antibody. C: hydroxyproline assay of lung lysates. D: picrosirius red staining of lung sections from mice treated with water (control vehicle) or bleomycin (3 U/kg) for 28 days. Data are means ± SE. P value, Student's t-test. Scale bar, 100 μm.