MTOR and head and neck squamous cell carcinoma: These findings agree with Pedrero et al. [19] who found that PIK3CA amplification is an early event in HNSCC in 43/117 (37%) cases, while Chaux et al. [13] analysed 112 PSCC cases and found low levels of p-AKT (Ser473) and p-mTOR (Ser2448) immunoexpression.