Gill et al., 2014 studied the Glioblastoma cell types in biopsies taken from Contrast-enhancing and non-enhancing regions (MRI-imaging) of human glioblastoma. They found that the Contrast-enhancing region (the tumor core) contains glioma cells that belong to mostly proneural, classical, or mesenchymal subtypes of GBM whereas the non-enhancing region (the margins of tumor) predominantly is enriched with neural subtypes.