TP53 and medulloblastoma: While SI-CSC Ptch;p53 MB samples exhibited differential expression of the genes in histone acetylation and methylation pathways in LDE225-treated tumors, there was no significant difference between vehicle- and LDE-resistant SD-CSC medulloblastomas (Fig. 3D), suggesting that these processes are not generic responses to SMOi treatment in all medulloblastoma subtypes; rather, they are specifically associated with SI-CSC tumors.