Collectively, in regard to the function of ABCG2 as one of the efflux transporter family, which has the ability to excrete cytotoxic drugs from cells, so as to be considered as a drug-resistant marker, and also a marker related to the inherent resistance or acquired resistance to chemotherapeutics in CSCs, we presume that ABCG2 might serve as a main contributor to promote colorectal cancer cell stem-like traits and drug resistance and plays a pivotal role in CRC development. The gene discussed is ABCG2; the disease is colorectal cancer.