ABCG2 and cancer: Several mediators associated with drug resistance in cancer cells have been found to be transferred via exosomes, including drug efflux pumps (e.g., P-glycoprotein, ATP-binding cassette transporter G2, and ABCG2), miRNAs, lncRNAs, and other regulators such as transient receptor potential cation channel subfamily C member 5 (25).