ANO1 and head and neck squamous cell carcinoma: Calcium-activated chloride channel ANO1 is also expressed in various cell types such as smooth muscle, epithelial cells, small sensory neurons, and olfactory-derived cells, and is highly amplified in human cancers such as prostate cancer, breast cancer, esophageal cancer, pancreatic cancer, oral squamous cell carcinoma, and head and neck squamous cell carcinoma [7].