ULBP1 and head and neck squamous cell carcinoma: For HNSCC patients with different expression levels of KLRK1 and its ligands, selective development of more effective targeted drugs may include targeting ULBP2/3 rather than upregulating KLRK1 or inhibiting ULBP1 for tonsil cancer and targeting ULBP1/3 rather than inhibiting ULBP2 for laryngeal cancer.