AKT1 and fibrosarcoma: VEGF subsequently binds to its receptors, activating downstream signaling cascades such as the phosphatidylinositol 3-kinase–protein kinase B and Rat sarcoma–Rapidly accelerated fibrosarcoma–mitogen-activated protein kinase kinase–extracellular signal-regulated kinase pathways, which promote endothelial cell proliferation, migration, and survival—key steps in tumor angiogenesis (73–75).