AKT1 and meningioma: Importantly, PDGF has been associated with activation of two main anti-apoptotic cell signaling pathways (Ras/mitogen-activated protein kinase [MAPK] and PI3K-Akt) and one secondary pathway (phospholipase C-gamma1–protein kinase C [PLC-γ1–PKC]) simulating meningioma proliferation via autocrine and paracrine mechanisms [13,53].