ABCG2 and breast cancer: In the mitoxantrone-resistant breast cancer cell line MCF-7/MX100 overexpressing ABCG2 transporter, miR-328 was able to increase the sensitivity to mitoxantrone by decreasing the ABCG2 protein expression via complementary targeting the 3′UTR of ABCG2 mRNA (Pan et al., 2009).