268) and blocks HH-induced ciliary accumulation of GLI2 (Ref. 267). The in vivo efficacy of ATO was demonstrated in both studies; it inhibits the growth of Ptch+/−/p53−/− medulloblastoma allografts and Ewing sarcoma xenografts and increases survival of constitutively activated SMO transgenic mice with MB (Refs 267, 268). This evidence concerns the gene SMO and medulloblastoma.