Interestingly, this study also indicates that the expression of the cell cycle regulator p21cip1/WAF1, which inhibits CDK2, is decreased in all cystic models while it is increased in the kidneys of Nphp4 mutant mice, again suggesting differential pathophysiological mechanisms between cystic infantile and juvenile forms of NPH. Here, CDK2 is linked to normal pressure hydrocephalus.