Through fusion between macrophages and breast cancer cells, expression of E-cadherin is downregulated and expression of N-cadherin, vimentin and snail are upregulated, together with increased expression of matrix metalloproteinase (MMP)-2, MMP-9, urokinase-type plasminogen activator (uPA), and S100A4. The gene discussed is CDH1; the disease is breast carcinoma.