Fig 1: Sphingolipidomic analysis after treatment with ARC39 in L929 cells. Cells were treated with 20 µM of ARC39 for the indicated durations and the endogenous levels of the following sphingolipids were determined by MS in whole-cell lysates: sphingomyelins (SMs) (A); ceramides (Cers) (B). Numbers indicate the chain length and saturation of the fatty acyl chain. C: dhSph, Sph, and S1P, respectively. D: Time-resolved fluorescence emission at 590 nm. Activity of rhSphK1 (left) and rhSphK2 (right) was determined in real-time after pretreatment with ARC39 as indicated. The reaction mixture contained 30 µM of NBD-C18-Sph, 150 nM of SphK1, or 6.9 nM of SphK2 with or without 1 mM of ATP. Data are represented as mean ± SD, n = 3 experiments. Two-way ANOVA was used followed by Bonferroni correction. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.