EGFR and glioblastoma: Interestingly, previous studies suggested the existence of direct effects of beta-adrenergic signaling in models of GBM, particularly in in vitro contexts, where both propranolol and isoproterenol suppressed the proliferation of human glioblastoma cell lines (58), and treatment of cancer cells with propranolol counteracts the epidermal growth factor receptor (EGFR) oncogenic traits (59), that is associated with GBM aggressiveness features.