PIK3CA and head and neck squamous cell carcinoma: To extend our findings beyond the UM‐SCC cell lines and examine whether PIK3C2A downregulation is also effective in HNSCC models with PI3K signaling pathway alterations, we also applied the same treatment strategy to another human HNSCC cell line Detroit 562, which has a gain‐of‐function mutation (H1047R) in the PIK3CA gene.