ABCB5 and colorectal cancer: Combined with the results that ABCB5 expression level is increased following 5-FU treatment, we consider that low expression level of ABCB5 in primary colorectal cancer tissues is because of a lack of 5-FU-based adjuvant chemotherapy, and ABCB5 expression level may be increased in recurrent colorectal cancer tissues survived following 5-FU-based adjuvant chemotherapy.