Fig. 1

Flowchart illustrating the experimental design. De novo glioblastomas were allocated to different radiographic groups according to their vicinity to the SVZ as proposed by Lim et al. [14]. Group I consisted of contrast-enhancing tumors contacting the SVZ and infiltrating the cortex, group II of tumors contacting the SVZ only, group III of tumors contacting the cortex only, and group IV of tumors contacting neither SVZ nor cortex. Accordingly, groups I and II tumors were pooled as SVZ+ GBM, groups III and IV tumors as SVZ– GBM. Location-dependent differential gene expression was investigated by mRNA microarray analysis (microarray cohort; n = 36 GBM) and was validated by qPCR in a confirmatory patient sample (validation cohort; n = 142 IDH1 wt GBM) with subsequent survival analysis by log-rank test and multivariate Cox regression analysis