ABCB1 and ABCG2 (ABCB1 (P-gp) and ABCG2 (BCRP))

ABCB1 (P-glycoprotein) and ABCG2 (Breast cancer resistance protein) are ATP-dependent efflux transporters located in the plasma membrane of many tissues, including intestine, liver, kidney, brain endothelium, and placenta[1][2][3][6][7]. ABCB1, initially identified in multidrug-resistant cancers, utilizes ATP hydrolysis to export a diverse range of lipophilic or amphipathic drugs out of cells, thereby protecting tissues from xenobiotics but also limiting drug efficacy by mediating multidrug resistance[1][3][7]. ABCG2 was discovered in drug-resistant breast cancer cells and similarly exports a wide array of drugs and endogenous compounds, including anti-cancer agents and metabolites[2][3][4]. Both transporters restrict drug penetration into sanctuary sites (e.g., brain, fetus) and are key determinants in the pharmacokinetics and safety profile of many therapeutic agents. Their clinical importance lies in their impact on chemotherapy resistance, drug interactions, and as potential targets for overcoming multidrug resistance in cancer therapy[1][2][3][5][7].

Other names

MDR1Multidrug resistance protein 1P-glycoproteinPgpBCRPBreast cancer resistance proteinMitoxantrone resistance protein

Drugs act as substrates (are pumped out of cells), inhibitors (block efflux to increase intracellular drug concentration), or modulators (affect transport activity)