The study investigates the role of E-cadherin in the invasiveness of human carcinoma cells. E-cadherin, a cell-cell adhesion molecule, is expressed in well-differentiated carcinomas but not in poorly differentiated ones. The authors found that E-cadherin-negative, invasive carcinoma cell lines could be transformed into noninvasive, E-cadherin-positive lines by transfecting them with E-cadherin cDNA. Conversely, the invasive behavior of E-cadherin-positive, dedifferentiated carcinoma cells was inhibited by treatment with anti-E-cadherin monoclonal antibodies. These findings suggest that E-cadherin acts as a suppressor of invasion in human carcinomas.The study investigates the role of E-cadherin in the invasiveness of human carcinoma cells. E-cadherin, a cell-cell adhesion molecule, is expressed in well-differentiated carcinomas but not in poorly differentiated ones. The authors found that E-cadherin-negative, invasive carcinoma cell lines could be transformed into noninvasive, E-cadherin-positive lines by transfecting them with E-cadherin cDNA. Conversely, the invasive behavior of E-cadherin-positive, dedifferentiated carcinoma cells was inhibited by treatment with anti-E-cadherin monoclonal antibodies. These findings suggest that E-cadherin acts as a suppressor of invasion in human carcinomas.