Identifying the interactions between candidate compounds and transporters is an important step in the development of drugs. Drug transporters, functioning as uptake or efflux pumps, are widely expressed in many tissues including intestinal enterocytes, hepatocytes, kidney proximal tubules, blood-brain barrier capillary endothelial cells. Drug-transporter interaction influences not only the bioavailability but also interactions between different drugs. Creative Bioarray has extensive expertise in determining whether a test compound act as a substrate or inhibitor of various transporters.