TGFB1 and pulmonary fibrosis: This widely-held opinion has been recently challenged by evidence from a mouse model54 in which ASMA-directed deletion of αv integrins did not prevent lung fibrosis in a bleomycin mouse model, suggesting that other subpopulations of fibroblasts that don’t express ASMA (the majority) contribute to the integrin-mediated TGFβ activation and collagen production in this model.