ATOH1 and medulloblastoma: Shh medulloblastoma develop at a significantly more rapid rate in p53−/−; Math1-Cre; SmoM2-eYFPloxP/loxP mice compared to p53+/+; Math1-Cre; SmoM2-eYFPloxP/loxP mice (Figure S2), indicating that the p53 pathway is essential to suppression of medulloblastoma formation in this model.