Furthermore, certain cell cycle–related proteins, including TOP2A, PCNA, MCM2, MCM4, MCM5, MCM6, and MCM7, have also been reported (69–71) to facilitate cancer cell proliferation, and the enhanced expression of these cell cycle–related proteins may contribute to uncontrolled ESCC cell proliferation. This evidence concerns the gene MCM2 and esophageal squamous cell carcinoma.