E-cadherin is a member of the cadherin family of $Ca^{2+}$-dependent cell-cell adhesion molecules. p120-Catenin and ${delta}$-catenin are known to bind to similar juxtamembrane regions of E-cadherin, and p120-catenin is known to stabilize E-cadherin. However, the function of competition between p120-catenin and ${delta}$-catenin for E-cadherin has not been fully explained. In this report, we show that cells overexpressing ${delta}$-catenin contain less p120-catenin than control cells at the cell-cell interface and that this causes the relocalization of p120-catenin from the plasma membrane to the cytosol. We show that successful binding by one to Ecadherin adversely affects the stability of the other.