Conditional repression of either Pkd1 (Pax8rtTA; TetO-cre; Pkd1fl/fl) (Shibazaki et al., 2008) or Pkd2 (Pax8rtTA; TetO-cre; Pkd2fl/fl) (Ma et al., 2013) results in kidney cysts within 10 weeks after the start of doxycycline induction, suggesting that expression of both genes is necessary to prohibit cyst development in mature mice. This evidence concerns the gene PKD1 and cyst.