These findings implicate AQP3 as a novel determinant of renal cyst enlargement and hence a potential drug target in ADPKD.-Wang, W., Geng, X., Lei, L., Jia, Y., Li, Y., Zhou, H., Verkman, A. S., Yang, B. Aquaporin-3 deficiency slows cyst enlargement in experimental mouse models of autosomal dominant polycystic kidney disease.