ADA and head and neck squamous cell carcinoma: Between the identified metabolism-related genes associated with the prognosis of HNSCC patients are 1-acylglycerol-3-phosphate O-acyltransferase 4 (AGPAT4); amylase alpha 2B (AMY2B); acyl-CoA dehydrogenase long-chain (ACADL); creatine kinase, muscle (CKM); and adenosine deaminase (ADA), which are related to energy and purine, phospholipids, and mitochondrial beta oxidation of fatty acid, among other metabolic proteins [87].