SPHK1 and hepatocellular carcinoma: Regarding S1P-effects on HCC cell migration, it has been shown that the level of sphingosine kinase 1, which catalyzes the phosphorylation of sphingosine to S1P, is increased in HCC tissues, and that sphingosine kinase 1 induces the migration of SMMC-7721 cells and HCCLM3 cells, the HCC cells, due to enhancement of S1P secretion [33].