Here, Youn et al. investigated how the primary cilium contributes to tumorigenesis and show that primary cilia are abundant in SHH and WNT medulloblastomas, but rare in G3 and G4 medulloblastomas, from 111 cases. Their findings reveal tumor type-specific ciliary functions, and they expand the function of primary cilia to translation control to show a molecular mechanism by which cilia regulate cell cycle progression.