Consistent with the basal methylation level in gastric cancer cell lines, the CpG island in the Sp1 binding site of the TLR4 promoter was dramatically demethylated by treatment with 1 μM 5-aza-dC of gastric cancer cell lines expressing low levels of TLR4 in AGS, SNU-216, SNU-668, NUGC-3, and MKN-74 cells (Figure 2C), accompanied by a dramatic increase in TLR4 mRNA levels in these cells (Figure 2D). This evidence concerns the gene SP1 and gastric cancer.