ABCG2 and cancer: Considering that normal and cancer stem cells are frequently identified based on their low accumulation of Hoechst 33342 dye due to ABCG2 overexpression [45], we can speculate that, in addition to resistance to chemotherapeutics drugs, ABCG2 may also control other important stem cell properties by modulating the influx and accumulation of different substrates including nutrients, with a selective advantage against neighbouring cells.