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). Here, WWTR1 is linked to head and neck squamous cell carcinoma.