BDNF and glioblastoma: The antigrowth effects of inhibiting P2X4R were consistent with previous evidence in glioblastoma multiforme (GBM), where P2X4R was shown to regulate cell growth via the brain-derived neurotrophic factor (BDNF)/Tropomyosin receptor kinase B (TrkB)/Activating Transcription Factor 4 (ATF4) signalling pathway [20,39].