We initially assessed the distribution and expression of E-cadherin in several human gastric cancer (HGC) cell lines at the protein level (Fig. 6a, Supplementary Figure 6A) as well as the mutation status at the mRNA and DNA levels (Supplementary Figures S6B and C), and divided them into three groups; E-cadherin-intact (MKN74 and MKN7), E-cadherin-mutant (MKN45 and KATOIII) and E-cadherin-low (AGS and HSC58). Here, CDH1 is linked to gastric cancer.