Here, we used the human non-small cell lung cancer NCI-H460 and its topotecan-selected NCI-H460/TPT10 subline, human colon cancer S1 and its mitoxantrone selected S1-M1-80 subline, as well as HEK293 cells stably transfected with an empty pcDNA3.1 vector or pcDNA3.1 vectors containing full-length wild-type (WT) or mutant-ABCG2. This evidence concerns the gene ABCG2 and colonic neoplasm.