SPHK2 and cancer: Sphingolipid-metabolizing enzymes control the dynamic balance of the cellular levels of important bioactive lipids, including the apoptotic compound ceramide and the proliferative compound sphingosine 1-phosphate (S1P), which is regulated by the sphingosine kinases SPHK1 and SPHK2, although SPHK2 appears to be more involved in cancer [17,18].