PF-543 (hydrochloride) is a potent, selective, reversible and sphingosine-competitive SPHK1 inhibitor with an IC50 of 2 nM and a Ki of 3.6 nM. PF-543 hydrochloride is >100-fold selectivity for SPHK1 over SPHK2. PF-543 (hydrochloride) is an effective potent inhibitor of sphingosine 1-phosphate (S1P) formation in whole blood with an IC50 of 26.7 nM. PF-543 (hydrochloride) induces apoptosis, necrosis, and autophagy.