This article is available online at http://www.jlr.org that FXR activation is benefi cial in situations of energy excess, such as obesity and diabetes, and FXR agonists are being evaluated in preclinical studies for treating diabetes and metabolic disorders ( 2, 3 ). Although FXR functions as a bile acid receptor, studies have identifi ed that FXR also regulates multiple drug metabolizing enzyme or drug transporter genes by binding to FXR response elements and promoting transcription of target genes, suggesting that FXR may play an important role in determining the pharmacokinetics and pharmacodynamics of numerous drugs ( 4 ).Recent pharmacogenetic studies have demonstrated that drug transporters, in particular the solute carrier organic anion transporter family, member 1B1 (SLCO1B1) and ATP-binding cassette, subfamily G, member 2 (ABCG2), play an important role in determining the pharmacokinetics and pharmacodynamics of statins ( 5-7 ). It is known that the tissue protein expression of drug transporters is highly variable between individuals and that these interindividual variations in transporter expression may result in variabilities in lipid response to statins ( 4 ). Loss of function single nucleotide polymorphisms (SNP) in the coding region of the SLCO1B1 and ABCG2 genes were associated with altered statin exposure and lipid-lowering effects ( 5-7 ), but these SNPs did not appear to affect overall protein expression ( 4,8 ). Instead, the decreased transport activity of SLCO1B1 and ABCG2 associated with these SNPs is thought to result from membrane-traffi cking defects ( 4, 9, 10 ).FXR regulates several drug transporters involved in statin disposition, including SLCO1B1, SLCO1B3, sodiumtaurocholate cotransporting polypeptide (NTCP), and The farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily, which is activated by bile acids. Activation of FXR leads to altered expression of many genes responsible for bile acid and lipid and glucose metabolism and transport, resulting in decreased intracellular bile acid concentrations and reduced plasma glucose and triglyceride levels ( 1, 2 ). Current evidence suggests