SMAD7 and esophageal squamous cell carcinoma: Using the P. gingivalis-associated molecules substantiated in the present study, which included CTGF, CYR61, PAI-1, Smad7, Snail, Oct4, E-cadherin, Vimentin, and MMP-9, we developed a set of P. gingivalis signature genes, including Snail and E-cadherin, to identify high-risk ESCC patients.