Mille et al. have shown that the sonic hedgehog (SHH) receptor BOC, which is required to form a functional complex with Patched (PTCH1), mediates medulloblastoma progression. The authors found that BOC is upregulated in medulloblastomas with activated SHH signalling. Inactivation of Boc in medulloblastoma mouse models reduced tumour size and progression. BOC increases cell proliferation by regulating levels of cyclin D1. BOC also promotes DNA damage, increasing the incidence of Ptch1 loss of heterozygosity, which drives tumour progression.