As VHL-wt ccRCC cell lines Caki-1 and SN12-PM6 with metastatic potential harbored high incidence of primary cilia and clinical patients with ciliation were more likely to experience relapse and metastasis, we proposed a novel hypothesis that primary cilia may have a tumor-promoting effect in VHL-wt ccRCC. This evidence concerns the gene VHL and nonpapillary renal cell carcinoma.