Regorafenib was also reported to reverse the P-gp- (Wang et al., 2017b) and ABCG2-mediated MDR (Zhang et al., 2019) in vitro in CRC cell line SW620/Ad300 (overexpressing P-gp) and S1-M1-80 (overexpressing ABCG2), respectively. The gene discussed is ABCG2; the disease is colorectal carcinoma.