Effects of sphingolipid administration on cell viability. NIH/3T3 cells were seeded into a 96-well culture plate. (A) C2 ceramide, phytoceramide and ceramide were dissolved in DMSO, and (B) yeast degradate, PHS and DHS were dissolved in EtOH. These sphingolipids were added to the cells for 24 h. Cell viability was measured using Cell Counting Kit-8. Cell viability is expressed as a relative value to vehicle control. (C) NIH/3T3 cells were transfected with 6 ×AP-1 reporter and TK Renilla luciferase vector for 24 h. Cells were treated with the indicated concentration of phytoceramide for 4 h. The luciferase activity was measured and expressed as fold change of control (Ctl). The results represent the means of triplicate determinations ± S.D. from a representative experiment.