ABCG2 and ovarian neoplasm: Increased levels of various transporters, such as ABCA1, ABCB5, and ABCC3/MRP3, have been demonstrated in ovarian tumour tissues, and an increased expression of ABCA1, ABCB1/MDR1/P-GP, and ABCG2/BCRP has been demonstrated in ovarian CSCs [66,67,68].