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