ABCG2 and cancer: Multidrug resistance (MDR) is a major obstacle for cancer therapy, most of which are related to the increased expression of drug efflux pumps.[41] Increasing studies suggest that EVs contain a variety of drug efflux pumps, such as transporters of the ATP‐binding cassette (ABC) superfamily including P‐glycoprotein (P‐gp/ABCB1/MDR1), ABC transporter G2 (ABCG2/BCRP), and multidrug‐resistant protein 1 (MRP1/ABCC1), which directly mediate the active extrusion of drugs.