ABCG2 and cancer: Because surface levels of P-glycoprotein and BCRP were not changed in KG1 and RPMI8226 cells, respectively, after the treatment with 3BrPA (Figure S1), these results suggest that ABC transporter activity is dependent on glycolysis in malignant cells, and that depletion of intracellular ATP by inhibition of glycolysis is able to inactivate ABC transporters to retain anti-cancer agents in malignant cells.