ABCG2 and lung cancer: Among these, ABCA2, ABCB1 (also known as P-glycoprotein or multidrug resistance 1 (MDR1)), ABCB4, ABCB11, ABCC1-6, ABCC10, ABCC11, and ABCG2 (also known as BCRP or MXR) have all been shown to be associated with the efflux and transportation of cytotoxic drugs (structurally diverse chemotherapeutic agents and their metabolites) from lung cancer cells, thus reducing intracellular drug concentrations [15].