ABCG2 and cancer: Our results, indicated that mitoxantrone, SN-38 and topotecan were efficacious in the non-resistant parental H460 and S1 cancer cells, whereas resistance occurred to these anticancer drugs in the ABCG2-overexpressing H460/MX20 and S1-M1-80 cancer cells, with a resistant-fold ranging from ∼30 to 70, consistent with our previous findings (Fan et al., 2018; Wu et al., 2022).