PAX5 and head and neck squamous cell carcinoma: In opposition, numerous studies functionally characterize PAX5 as a tumor suppressor in hepatocellular carcinoma [73,100], breast carcinoma [75,101,102,103], esophageal squamous cell carcinoma [72], retinoblastoma [104], gastric cancer [74,105], Merkel cell carcinoma [106], ovarian cancer [107], and head and neck squamous cell carcinoma [76].