SPHK1 and infection: Since our sphingolipidome profiling revealed increased Sph levels, but not S1P, upon Ctr infection in M2Φ and PMNs, we were surprised to measure significantly increased transcript levels for SPHK1 in both cell types, as early as 2 h p.i., as well as in FT190 cells 24 h p.i. (Fig. 2b).