Colonic and rectal polyps, which spontaneously develop in Apcmin/+ mice, showed an evident overexpression of the murine homologue of hERG1, mERG1 and the long-term treatment of Apcmin/+ mice with the specific hERG1 blocker, E-4031, suppressed polyp formation in the large intestine. This evidence concerns the gene KCNH2 and rectal hyperplastic polyp.