Description_x000D_ Biochem/physiol Actions_x000D_ MP-A08 is a highly selective ATP-competitive sphingosine kinase inhibitor that targets both SK1 and SK2. It is more selective and acts by different mechanisms than other SK inhibitors. MP-A0 targets the ATP-binding pocket, rather than the sphingosine binding pocket, with Ki values of 6.9 and 27 μM, respectively. Also, both SKI-II and PF-543 are thought to act in part by targeting sphingosine kinase for proteasomal degradation, which is not the case with MP-A08. MP-A08 was found to suppress the growth of human lung tumor xenografts in mice, both inducing apoptosis and inhibiting angiogenesis.