Although previous reports have not examined the expression or distribution of S1P3 in the lungs of IPF patients or bleomycin-induced fibrosis models directly, our results showed that the degree of pulmonary fibrosis and the concentration of CTGF in BALF were dependent on the expression of S1P3, not differences in S1P levels in WT and S1P3 KO mice. This evidence concerns the gene CCN2 and fibrosis.