In contrast, expression of calpain-6 was downregulated in head and neck squamous cell carcinoma (HNSCC), and decreased expression of calpain-6 was associated with tumorigenesis and poor prognosis in HNSCC, suggesting that calpain-6 could function as a tumor suppressor protein in HNSCC45. This evidence concerns the gene TCHP and head and neck squamous cell carcinoma.