SPHK1 and prostate cancer: FTY720 inhibits SPHK1, and its phosphorylated equivalent modulates S1P receptors [71,72]; PF543 is a nM potent selective inhibitor of SPHK1 [73]; SK1-II acts as dual SPHK1/SPHK2 inhibitor; and ABC294640 is a selective μM potent SPHK2 inhibitor [74], but in androgen independent prostate cancer cells can also induce the proteasomal degradation of SPHK1 [75].