AVPR2 and cyst: At the molecular level, mTOR and cAMP related signalling has been shown to drive cyst growth in many models of PKD and both the PCK rat and our PKD mice are capable to respond to inhibitors of those signalling pathways (i.e. sirolimus as an mTOR inhibitor and tolvaptan as a vasopressin V2 receptor antagonist capable of reducing [cAMP]i)7,58.