Notably, WWTR1 gene locus (3q25) is at close proximity to the locus of PIK3CA, SOX2 and TP63 at 3q26-28, whereby their focal amplification is frequently reported in HNSCC (The Cancer Genome Atlas Network, 2015; Figure 3—figure supplement 2C). Here, PIK3CA is linked to head and neck squamous cell carcinoma.