SPHK1 and cancer: Akt/mTOR (mammalian target of rapamycin) signaling is often activated in cancer and was previously shown to impact HIF-2α expression.35 To explore whether the loss of HIF-2α expression induced by SphK1 silencing was correlated with the inhibition of mTOR signaling, we examined the effect of siSphK1 on levels of total or phosphorylated forms of mTOR (p-mTOR) in A498 and 786-O cells.