PIK3CA and head and neck squamous cell carcinoma: Our pathway activation prediction analysis further confirms previously reported observations that despite the remarkable complexity of genomic alterations in HNSCC, most of them fall within a few major canonical driver-signaling pathways, and converge the activation of PI3K/AKT/mTOR, RAS/RAF/MAPK, JAK/STAT, WNT/β-catenin and TGFβ molecular networks.