AKT1 and central nervous system cancer: Several studies have illustrated that serum-free culturing conditions impact on several intracellular signaling pathways; for example AMP-activated protein kinase (AMPK) in skeletal muscle cells14, Mitogen-activated protein kinases (MAPKs) pathway in cardiac fibroblasts19 and protein kinase B (AKT/PKB) in glioma cells as well as in embryonic fibroblast cells20, 21.