Purity >95%. FTY720 is an immune modulator that down-regulates sphingosine-1-phosphate (S1P) receptors, enhances the activity of the sphingosine transporter ABCB1 and the leukotriene C4 transporter ABCC12 and inhibits cytosolic phospholipase A2 activity. It is known that some of the effects of FTY720 require its phosphorylation by sphingosine kinases in vivo, with FTY720-phosphate binding to and down-regulating S1P receptors. Biotin-FTY720 is a biotin-tagged analog of FTY720. The hydroxy methyl side chain of FTY720 that is targeted for phosphorylation by sphingosine kinases is retained in this analog, suggesting that it would likewise be phosphorylated in vivo .