delta-Catenin is a member of the p120-catenin subfamily of armadillo proteins. Here, we describe distinctive features of delta-catenin localization and its association with E-cadherin in HEK293 epithelial cells. In HEK293 cells maintained in low cell densities, approximately 15% of cells overexpressing delta-catenin showed dendrite-like process formation, but there was no detectable change in RhoA activity. In addition, delta-catenin was localized mainly in the cytoplasm and was associated with p190RhoGEF. However, at high cell densities, delta-catenin localization was shifted to the plasma membrane. The association of delta-catenin with E-cadherin was strengthened, whereas its interaction with p190RhoGEF was weakened. In mouse embryonic fibroblast cell, ectopic expression of E-cadherin decreased the effect of delta-catenin on the reduction of RhoA activity as well as on dendrite-like process formation. These results suggest that delta-catenin is more dominantly bound to E-cadherin than to p190RhoGEF, and that delta-catenin's function is dependent on its cellular binding partner. (C) 2008 Elsevier Inc. All rights reserved.