LPAR1 and idiopathic pulmonary fibrosis: Lysophosphatidic acid (LPA), a multifunctional phospholipid, plays an important role in the pathogenesis of IPF and leads to fibroblast growth, proliferation, and migration.44 A previous study reported that the concentration of LPA in broncho-alveolar lavage (BAL) fluid of patients with IPF was clearly, obviously higher than that of healthy controls.45 In a bleomycin mouse model of pulmonary fibrosis, the concentration of LPA in BAL fluid markedly increased after 5 days,45 and LPA1-deficient mice showed significant resistance to bleomycin-induced IPF.