MCM2 and esophageal squamous cell carcinoma: The potential anti-ESCC mechanism following DIM+DFMO treatment was that through downregulation of the Cell Cycle and DNA Replication associated proteins (MCM2/3/5/6/7, CDK1 and LIG1), the hyperactive activities of these signaling pathways were suppressed and lead to the inhibition of tumor proliferation in ESCC patients (Figure 5I).