TF and glioblastoma: Loss ofPTENexpression is common in all glioblastoma subtypes, with 20 to 40% of glioblastoma tumors harboring inactivatingPTENmutations and roughly 80% demonstrating loss ofPTENexpression, e.g., byPTENpromoter methylation.113, 114PTENinactivation leads to upregulation of RAS and mTOR signaling and subsequent overexpression of TF, similarly to activation ofEGFR.