ABCG2 and cancer: Of note, 10 μM TMP195 alone had no significant apoptotic effect in all tested cell lines, raising the possibility that TMP195 enhances drug-induced apoptosis and reverses drug resistance in cancer cells overexpressing ABCB1 or ABCG2 through modulation of the function and/or protein expression of ABCB1 and ABCG2.