PKD1 and Kidney Cyst: 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.