Peroxisome proliferator-activated receptor α (PPARα) is a ligand-activated transcription factor involved in the regulation of lipid homeostasis. Activation of PPARα results in expression of a variety of genes, particularly those involved in fatty acid β-oxidation, binding, and transport. Clofibrate is a PPARα agonist and a member of a class of hypolipidemic drugs that includes fenofibrate and benzafibrate, which have been used clinically to treat dyslipidemia and cardiovascular disease. In a transactivation assay, clofibrate exhibits EC50 values of 50 and 55 μM for mouse and human PPARα, respectively. It also binds to PPARγ, but with 10-fold less affinity and is inactive at PPARδ at concentrations up to 100 μM.