Genetic and/or non-genetic causes for inter-individual and inter-cellular variability in transporter protein expression: implications for understanding drug efficacy and toxicity.

Introduction: Drug transporters are differentially expressed in many polarized tissues. The varied distribution and expression of transporters determines the net transcellular transport and influences the disposition of many clinically used drugs. ATP-binding cassette (ABC) and Solute Carrier (SLC) transporters interact dynamically to mediate the passage of drugs across cells.