The PAR4 gene knockdown was able to upregulate the levels of DNMT1 and HDAC2 proteins and genes and suppress p16 protein and gene expression following transfection of PAR4-siRNA with ESCC cells (P > 0.05) (Figures 4(a) and 4(b)). This evidence concerns the gene DNMT1 and esophageal squamous cell carcinoma.