TGFB1 and asthma: PAI-1 is located in the downstream of TGF-β1 and TGF-β1/Smad induced elevating PAI level and skin fibrosis17 and it is highly expressed in some reversible lower respiratory diseases, like asthma.19, 20 Among many genes modulated by TGF-β1,higher PAI-1 levels facilitate tissue fibrosis in asthma patients.19, 20, 21 TGF-β1 induced the expression of PAI-1 as part of the TGF-β1-activated esophageal fibrosis network.21