The receptor tyrosine kinase EGFR also has been shown to activate YAP/TAZ independently of PI3K through the direct phosphorylation of MOB1A; this is discussed in detail below (please see ‘FAT1-Independent Mechanisms of Oncogenic Hippo Pathway Perturbation in HNSCC’) [44]. This evidence concerns the gene PIK3CA and head and neck squamous cell carcinoma.