RB1 and glioblastoma: Several proteins are commonly altered in glioblastoma, including IDH1, EGFR, TERT, tumor protein p53 (TP53), phosphatase and tensin homolog (PTEN), neurofibromatosis type 1 (NF1), platelet-derived growth factor receptor α (PDGFRA) and retinoblastoma 1 (RB1) [25].