Activation of PPARα by three PPARα agonists. Primary hepatocytes were co-transfected with a luciferase reporter construct containing PPRE and with or without PPARα/RXR expression vectors. Twelve hours after transfection, three PPARα agonists, bezafibrate, fenofibrate and WY-14,643 were added at the concentrations as indicated. Cells were harvested after 24 h drug treatment. Luciferase activity was normalized against β-galactosidase activity. The groups having three bars indicate different treatments with the concentrations of 10, 30 and 100 μM, from left to right. Error bars represent standard derivations of two replicates.