Effect of phytoceramide on transcriptional activity of PPARα in HEPG2 hepatocytes. HEPG2 cells were transfected with 4 × PPRE reporter plasmid and expression vectors for PPARα and RXR. TK Renilla luciferase reporter was cotransfected for normalizing the transfection efficiency. Following transfection, cells were treated for 24 h with phytoceramide (1, 10 μM). Luciferase assays were performed as described elsewhere. All results are shown as means ± S.D. (n = 3). *P < 0.05, significantly different from the level of vehicle control.