The stumpy gene is required for mammalian

iliaareevolutionarilyconservedorganellesandaregenerallyclassified as primary (sensory, nonmotile) or motile [e.g.,those expressed by ependymal cells in the brain that generateforce necessary for cerebrospinal fluid (CSF) flow] (1, 2). Theloss or defective function of cilia has been implicated in diseasessuch as obesity, diabetes, situs inversus, hydrocephalus (HC),and polycystic kidney disease (PKD) (3–8). The mechanismsregulating growth and stability of mammalian cilia during de-velopment are poorly understood. In attempting to explore thefunctionofthetransforminggrowthfactor 1gene(