PIK3CD and central nervous system cancer: In depth, phenotypically, the overexpression or amplifications of EGFR and the expression of the EGFRvIII variant (EGFR lacking exons 2–7 encoding the extracellular domain) are commonly observed in glioma and are associated with resistance, leading to cell proliferation, differentiation, and survival through the activation of the PI3K/AKT/mTOR pathway (16, 24).