ABCG2 and neoplasm: This is important because,despite many efforts, blocking these transporters by small-moleculeinhibitors has thus far not resulted in improved tumor responses inclinical studies.23,25 Therefore, anthracyclines, whichare both potent killers of tumor cells and insensitive to ABC transporter-mediatedexport, may be attractive alternatives, especially if novel variantsare less toxic to healthy tissues.