ABCG2 and colonic neoplasm: The assay was performed with a parental HT29 colon cancer cell line (HT29par) and a HT29 colon cancer cell line made resistant to SN-38 (HT29SN38), of which the latter has previously been shown to be upregulated in the ABCG2 gene and to be overexpressing ABCG2/BCRP [22].