Figure 2.

Involvement of S1P in cell apoptosis and cell proliferation. Divergent cellular effect via sphingosine kinase isoform activation. Increasing of cellular proliferation and migration by growth factors and cytokines depend on SPK1 activation and promotion of apoptosis by activation of SPK2. Elimination of S1P via different ways: dephosphorylation reactions catalyzed by S1P-specific phosphatases that require the coenzyme pyridoxal 5′-phosphate and a specific pH range (7.4–7.6) or by enzymes belonging to the nonspecific lipid phosphate phosphatase family (LPPs) which are important in controlling local S1P levels within specific tissue niches. Abbreviations: SPK1—sphingosine kinase 1; SPK2—sphingosine kinase 2; SPL—S1P lyase; LPPs—lipid phosphate phosphatase.