P2RY2 and pulmonary fibrosis: Increased extracellular ATP levels have been measured in the bronchoalveolar lavage (BAL) fluid derived from IPF patients or animals with bleomycin-induced pulmonary fibrosis, whereas deficiency in distinct P2R subtypes such as P2X7R or P2Y2R was associated with reduced inflammation and fibrosis following bleomycin administration (12–14).