USP15 and glioblastoma: In order to evaluate whether the here delineated regulation of the WNT pathway through USP15 is of relevance in human GBM, we interrogated the relationship between expression of USP15 and the prototypic WNT target gene AXIN2 in human GBM samples using the TCGA dataset (n=107; normalized level 3 RNAseq data).