Secondly, glioblastoma can be sub-classified into proneural, neural, mesenchymal, and classical according to differential gene expression profiles, as well as the mutation status of certain key genes including platelet-derived growth factor receptor (PDGFRA), neurofibromatosis type 1 (NF1) and epidermal growth factor receptor (EGFR) [139,140]. This evidence concerns the gene EGFR and glioblastoma.