However, the function of UCH-L1 in tumor initiation, progression and invasion is still controversial, as UCHL1 methylation has been reported in multiple tumors, including nasopharyngeal 56, esophageal 57, gastric 58, renal 59, head and neck squamous cell carcinoma 60, hepatocellular 61, and ovarian cancers 62, supporting a critical role in tumor suppression. This evidence concerns the gene UCHL1 and head and neck squamous cell carcinoma.