The basis for the association of normal immature cerebellum with SHH-activated medulloblastoma is not entirely clear, but may be influenced by the differential expression of SHH pathway genes during normal cerebellar development, when SHH signaling from the Purkinje cells functions as a key driver of proliferation and differentiation for granule neurons [5, 9]. The gene discussed is SHH; the disease is medulloblastoma.