Our findings reinforce the idea that Thy-1 expression in fibroblasts modulates their responses to inflammatory mediators, which may account for the more severe lung fibrosis in Thy-1 deficient mice and the predominance of Thy-1− fibroblasts in the fibroblastic foci in patients with idiopathic pulmonary fibrosis [19]. Here, THY1 is linked to idiopathic pulmonary fibrosis.