Blocking DNA methylation with azacitidine, a DNA methyltransferase-inhibiting cytosine nucleoside analogue upregulated CBS mRNA expression in all cell lines tested except Hs746T, whereby SNU-1 cells showed a>50-fold increase, confirming epigenetic silencing of CBS expression in gastric cancer cells (Figure 6—figure supplement 1E). This evidence concerns the gene CBS and gastric cancer.