MTOR and glioblastoma: The GBM development is characterized by many mutations among different key signaling pathways, including the receptor tyrosine kinase (RKT) ones [82,83], such as the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mTOR pathway and the Ras/MAPK/ERK pathway, which are involved in the regulation of cell proliferation, survival, differentiation and angiogenesis.