A potent inhibitor of SK1 (IC50 = 2-3.6 nM) that less effectively inhibits SK2 (IC50 = 356 nM); prevents the phosphorylation of sphingosine in cancer cells and in whole blood (EC50s = 8.4 and 27 nM, respectively); prevents sickling, hemolysis, and inflammation in sickling cell disease transgenic mice.