SPHK1 and HIV-1 infection: Harnessing the established safety and efficacy of FTY720, we built upon our recent report of its ability to reduce HIV-1 cell-to-cell transmission (14) and hypothesized that reduced availability of S1P via SPHK inhibition also may be effective at inhibiting HIV-1 infection and, importantly, specific, as one or both isoforms of sphingosine kinase can be targeted.