SPHK1 and fibrosis: The increased S1PL expression in LPS- [34] and VILI-induced mouse lungs (Figure 1) correlated with decreased S1P levels; however, in pulmonary fibrosis both SphK1 and S1PL expressions were elevated and blocking S1PL accentuated bleomycin-induced pulmonary fibrosis [23] suggested a protective role of S1PL in fibrosis.