Pharmacogenomic importance of ABCG2.

The ATP-binding cassette transporter ABCG2 (BCRP, MXR and ABCP) is highly expressed in the gastrointestinal tract and liver, and governs absorption, distribution and excretion of a wide variety of clinically important drugs. Common germline polymorphisms in the ABCG2 gene have been described that can affect expression, cellular localization and/or substrate recognition of the encoded protein. Alteration of transporter function by either of these mechanisms contributes significantly to interindividual variability in drug disposition and treatment outcome with certain, but not all, substrates for ABCG2.