VIP and malignant colon neoplasm: In previous studies, it has been reported that a gastrointestinal hormone such as vasoactive intestinal polypeptide (VIP) caused Verner–Morrison syndrome, which is associated with diarrhea [32]; diarrhea occurs after the intravenous administration of VIP to healthy individuals [33]; and AQP3 expression levels increase after VIP treatment in HT-29 cells derived from human colon cancer [24].