ATP-binding cassette subfamily B member 1 (ABCB1) and ATP-binding cassette subfamily G member 2 (ABCG2) (ABCB1 and ABCG2)

ABCB1 (P-glycoprotein/MDR1) and ABCG2 (BCRP) are major human ATP-binding cassette transporters that actively pump a wide variety of substrates—including many drugs—out of cells using energy from ATP hydrolysis. They are highly expressed in tissues involved in drug absorption and excretion (intestine, liver, kidney, blood-brain barrier) and are functionally associated with multidrug resistance, especially in tumor cells. Overexpression of either protein contributes to reduced intracellular drug levels and clinical resistance to chemotherapy. These proteins are also implicated in drug-drug interactions and variability in therapeutic response due to genetic polymorphisms and differential tissue expression.

Other names

P-glycoproteinMDR1multi-drug resistance protein 1 (MDRP1)Breast cancer resistance protein (BCRP)MXRABCP

Efflux of drugs out of cells, lowering intracellular concentrations and efficacy. Confer resistance to chemotherapy by reducing drug accumulation in tumor cells.