Sphingosine-1-Phosphate (S1P) is a signaling sphingosine, which is the product of the phosphorylation of sphingosine by sphingosine kinase. S1P is dephosphorylated by sphingosine phosphatase to form sphingosine, and can be irreversibly degraded by sphingosine phosphate lyase. Many cells can secrete S1P, which then affects other cells in an autocrine or paracrine manner.