Previously, we have shown that heparan sulfate (HS) 6-O-endosulfatase 1 (Sulf1) is a transforming growth factor-β1 (TGF-β1)-responsive gene in normal human lung fibroblasts and functions as a negative feedback regulator of TGF-β1 and that TGF-β1 induces the expression of Sulf1 as well as that of the closely related Sulf2 in a murine model of pulmonary fibrosis.