AQP1 is overexpressed in the pancreatic ducts of patients with autoimmune pancreatitis, which showed chronic pancreatitis characterized by a severely impaired secretion of digestive enzymes from acinar cells as well as pancreatic fluid and HCO3- secretion from ducts (Ko et al., 2009; Koyama et al., 2010). Here, AQP1 is linked to chronic pancreatitis.