Finally, qPCR (Fig. 1J) and western blotting (Fig. 1K) were performed to measure USP25 mRNA and protein levels in head and neck cell lines, including normal human oral keratinocyte (HOK), and HNSCC cell lines, and the results indicated that USP25 expression was decreased in all HNSCC cell lines compared with that in HOK cells. Here, USP25 is linked to head and neck squamous cell carcinoma.