CCNA1 and esophageal squamous cell carcinoma: We identified many candidate tumor suppressor genes (TSGs), such as PGP9. 5 in head and neck squamous cell carcinoma (HNSCC) [2], esophageal SCC (ESCC) [6], gastric cancer [4], and other cancers [7], NMDAR2B in ESCC [3] and gastric cancer [8], and CCNA1 in HNSCC [2].