E-Cadherin is a transmembrane glycoprotein that plays a key role in cellcell adhesion in epithelial tissues (1-2). The adherens junction between epithelial cells is comprised of extracellular domains of E-Cadherin from adjacent cells, which interact through a molecular zipper motif. In normal tissues, immunostaining of E-Cadherin is localized to the membrane of epithelial cells, consistent with its role in cell adhesion. Immunohistochemical studies have shown E-Cadherin to be expressed in breast ductal carcinoma with loss of expression in lobular carcinoma (1-2). As a result, mouse monoclonal anti-E-Cadherin [HECD-1 has been used by pathologists to differentiate between ductal and lobular carcinomas of the breast, with currently published sensitivity and specificity of approximately 90% (3). Rabbit monoclonal E-Cadherin antibody may combine the best properties of both monoclonal antibodies and rabbit antisera.