Immunohistochemical (IHC) evaluation studies of tissue sections [34] or TMA (tissue microarray) [10] from HNSCC patients—including specimens ranging from normal to metastatic stage and originating from the tongue, oral cavity, lip, larynx, and lymph-nodes—(Figure 2) displayed an upregulation of GLS enzyme expression in tumor tissues compared to normal mucosa (Table 2). This evidence concerns the gene GLS and head and neck squamous cell carcinoma.