FAS and glioblastoma: Since the above studies demonstrate that EGFR signaling is central to FAS in GBM, it is no surprise that GBM with the EGFR variant III amplification (EGFRvIII+, the most common EGFR gain-of-function mutation in GBM) has a higher proliferative rate owing to increased de novo lipogenesis and overall metabolic activity (34, 35).