AQP5 and Keratoconjunctivitis sicca: In Sjögren’s syndrome, ER stress activates and induces MMP9 activation through the FOX/MAPK pathway, which increases proteolytic activity and results in DES.452 Additionally, MAM functions in this syndrome, during which it can activate ER stress and inflammation.453 In aquaporin 5-deleted mice, the secretion of the lacrimal gland is injured, and there are symptoms of dry eye.454 Moreover, GRP78, CHOP, Caspase12, and BAX levels increase, indicating the occurrence of ER stress.454 High osmotic pressure induces dry eye through GADD34.455