PKD2 and cystic kidney disease: We observed no morphological changes of the kidneys from the Pkd1-, Pkd2-, and the Kif3a-KO mice 2 weeks after the induction (at the age of 8 weeks) and observed some dilated kidney tubules after 5 weeks of induction; renal cysts developed from 8 weeks of induction in Pkd1 and Pkd2 KO mice (20).