ABCG2 and cancer: Functioning primarilly as a defensive transporting pump, ABC sub-family G member 2 (ABCG2) can uptake its cellular substrates, including many cytotoxic agents such as anticancer drugs that are structure different, and then move them out of cancer cells, leading to acquired drug resistance (Chen, 2011; Kathawala et al., 2015; Falguieres, 2022; Fan et al., 2023).