PIK3CB and head and neck squamous cell carcinoma: The PIK3CA gene, which encodes the catalytic subunit p110α of class IA PI3K, can be mutated in a variety of cancers, such as head and neck squamous cell carcinoma, breast cancer, lung cancer, hepatocellular carcinoma, and ovarian cancer, among others.[19] Mutations in PIK3CA in cancer have been shown to be strongly associated with poor prognosis and resistance to standard treatments such as monoclonal antibody therapy and chemotherapy in cancer patients.[20] Not only cancer, PIK3CA is also associated with a variety of fibrotic diseases.