To determine whether methylation or lack of methylation at the CpG site on the TLR4 promoter influences Sp1 binding, we first carried out quantitative chromatin immunoprecipitation (qChIP) to identify the Sp1 binding site on the TLR4 promoter in SNU-638, SNU-216, and SNU-668 gastric cancer cells which show differential expression of TLR4 mRNA as shown Figure 2D (Figure 3A). Here, TLR4 is linked to gastric cancer.