These phosphotyrosine residues then serve as docking sites for proteins which initiate the activation of key signaling pathways like the mitogen-activated protein kinase (MAPK)- or the PI3K-activated protein kinase B (AKT)-pathway; key regulators of HNSCC cell proliferation, tumor growth, invasion and metastasis [4, 6]. This evidence concerns the gene AKT1 and head and neck squamous cell carcinoma.