Finally, we determined that reversal of promoter methylation by treatment with 5-aza-2′deoxycytidine partially rescues OTX2 expression (Fig. 5C), indicating that promoter methylation actively represses OTX2. In sum, these results indicate that OTX2 promoter methylation is sufficient for gene repression in medulloblastoma, and that an unmethylated promoter is necessary (but not sufficient) to permit OTX2 expression. This evidence concerns the gene OTX2 and medulloblastoma.