MKI67 and colonic neoplasm: In patients with colon cancer, a US phase I clinical trial (NCT01950403) showed that administration of linaclotide (870 μg/d) for 7 days after oral preparation of the intestine with polyethylene glycol increased the level of cGMP and reduced the proportion of Ki-67-positive colon epithelial cells (a higher proportion of Ki-67-positive cells suggested a faster rate of cell proliferation).