EGFR TKI gefitinib was demonstrated as a potential substrate for BCRP/ABCG2[15], [16], [17], [18], and combinatory treatment with gefitinib was also found to overcome the BCRP/ABCG2-mediated resistance to some anti-cancer drugs[31], [32], [33], [34], [35]. This evidence concerns the gene ABCG2 and cancer.