Expression of E-cadherin, α, β and γ-catenin and p120ctn, and of the adenomatous polyposis coli protein (APC), together with function of the cadherin–catenin complex was examined in a panel of gastric carcinoma cell lines, using immunocytochemistry, Western blotting and a cell–cell aggregation assay. The gene discussed is APC; the disease is gastric carcinoma.