Recent studies have shown that S1P plays a crucial role in tissue fibrosis (Pyne et al., 2013; Schwalm et al., 2013), and the tissue and/or plasma concentrations of S1P are associated with a variety of fibrosis factors, including transforming growth factor β (TGF-β), platelet-derived growth factor (PDGF), and connective tissue growth factor (CTGF) (Sauer et al., 2004). Here, CCN2 is linked to fibrosis.