These data are consistent with a model in which ZIC1 expression represses cell growth in maturing unipolar brush cell (UBC) progenitors of the RL-SVZ (origin of G4 medulloblastoma)2,3, whereas it promotes growth of GNPs (origin of SHH medulloblastoma) in the developing cerebellar external granule layer (EGL). Here, ZIC1 is linked to medulloblastoma.