We have demonstrated that the expression levels of Pol ι are positively correlated with that of MMP-2 and MMP-9 in ESCC tissues, and that Pol ι increases the expression of MMP-2 and MMP-9 in ESCC cell lines (Figure 1E, 1F and Figure 6). The gene discussed is MMP9; the disease is esophageal squamous cell carcinoma.