AQP5 and Keratoconjunctivitis sicca: Because the symptoms of dry mouth and dry eyes are suspected to be caused by the destruction of exocrine organs such as salivary glands and lacrimal glands, we then assessed the preferential targeting of acinar cells and ductal cells undergoing apoptosis by immunofluorescence using antibodies that recognize a broad array of keratins (pan-CK) and aquaporin 5 (AQP5) to define acinar (pan-CK+AQP5+) and ductal (pan-CK+AQP5−) cells in pSS tissue lesions35–37.