FTY720 Phosphate is a derivative of ISP-1 (myriocin) that is a fungal metabolite of the Chinese herb Iscaria sinclarii and a structural analog of sphingosine. FTY720 is a novel immune modulator that prolongs allograft transplant survival in numerous models by inhibiting lymphocyte emigration from lymphoid organs. It is phosphorylated by sphingosine kinase to the physiologically active phosphoric acid ester. FTY720 phosphate acts as a potent agonist at four of the sphingosine-1-phosphate (S1P) receptors (EDG-1, EDG-3, EDG-4, and EDG-5), with IC50 values of 0.2-6 nM.