SPHK1 and Myocardial fibrosis: Sphingosine-1-phosphate receptor 3 (S1PR3) deletion partially inhibited cardiac fibrosis in transgenic mice with overexpression of SPHK1, therefore the authors concluded that SPHK1-dependent myocardial fibrosis involved the S1PR3-Rho family small G protein signaling pathway, and the release of reactive oxygen species and the activation of TGF-β (22).