PKD1 and cyst: A possible explanation includes three points: (1) collecting duct cells are significantly more prone to originate cysts associated with PKD1/Pkd1 or PKD2/Pkd2 deficiency, since in ADPKD the preferential cyst origin is the collecting duct; (2) cyst formation originates from an absolute minority of cells from an absolute minority of nephrons; and (3) in this scenario, even expression of nestin in an extremely low number of collecting duct cells (not enough to be detected in previous studies) along a certain time period could potentially lead to significant cyst development from such cells.