Hypothesized pathways of gliomagenesis based on recent TCGA data. Hypothesized pathways of gliomagenesis based on TCGA data leading to the formation of subtypes of GBM: mesenchymal, classical, proneural and GBM-O. GBM, glioblastomas; IDH, isocitrate dehydrogenase; TCGA, The Cancer Genome Atlas.