RB1 and glioblastoma: EGFRvIII-expressing, temozolomide-resistant glioblastoma cells upregulate E2F6, an Rb-independent transcriptional repressor that promotes double-stranded DNA break repair [100], and tumor necrosis factor (TNF)-α secreted by TAMs regulates the conversion of proneural subtype GSCs into chemo- and radioresistant mesenchymal subtypes [101].