AVPR2 and autosomal dominant polycystic kidney disease: Tolvaptan, an oral V2 vasopressin receptor (V2R) antagonist which lowers [cAMP]i in cystic kidney tissues has been recently shown to delay progression of ADPKD in two large randomized clinical trials (Torres et al., 2012; Torres et al., 2017) and is now approved for clinical use in multiple countries.