SPHK1 and Uterine leiomyoma: The SphK-mediated pathway and SMase2-mediated pathway prevent the apoptosis of uterine leiomyoma cells and the proliferation of hepatic stellate cells, respectively (29, 50), whereas the SMase2/ceramide-mediated pathway regulates glucose uptake in 3T3-L1 preadipocytes and adipocytes in the absence of ET-1 (51–53).