To investigate whether ATF3 was regulated by β-catenin and TCF3 in GC cells, the expression of β-catenin and TCF3 was knocked down in MGC-803 and MKN-45 cells by infection with a specific shRNA lentivirus (Supplementary Fig. 4c-i, -ii and 4d-i, -ii). Here, ATF3 is linked to infection.