fig3

Figure 3. Overview of sphingosine 1-phosphate (S1P) biosynthesis and receptors. Ceramides are converted into sphingosine under the action of ceramidase. Sphingosine is then metabolized in S1P by the action of two sphingosine kinases (SphK1 and SphK2). All biosynthesis steps are reversible in cells. S1P activates five specific G protein-coupled receptors (S1P_1-5).