PIK3CA and head and neck squamous cell carcinoma: PIK3CA WT and H1047R overexpression slightly increased YAP/TAZ and CTGF/CYR61 more than those of vector alone, however, BYL719 treatment failed to inhibit EGFR-induced pYAP reduction, TAZ increase, and CTGF and CYR61 protein expression (Supplementary Fig. S4a and b), which is consistent with our prior results in HNSCC cells (Fig. 1f and g).