The transmembrane, calcium dependent molecule E-cadherin is considered to be one of the key molecules in the formation of the intercellular junctional complex and establishment of polarity in epithelial cells. Catenins, the alpha-subunit (102 kDa), beta-subunit (88 kDa) and gamma-subunit (82 kDa), [reviewed in Takeichi, 1991] are a group of proteins that interact with the intercellular domain of E-cadherin, resulting in complexes of E-cadherin/beta-catenin/alpha-catenin or E-cadherin/gamma-catenin/alpha-Catenin (Hinck et al., 1994). Beta-catenin, the vertebrate homologue of Drosophila segment polarity gene armadillo, and key element of the Wnt signal transduction pathways, is important in embryogenesis, cell transformation, and intercellular adhesion including the adhesion, motility and metastasis of cancer cells. Thus, catenin protein expression, regulation and localization are potentially important markers to predict motility and invasiveness of epithelial neoplasms. The regions of both alpha- and beta-catenin, located on 5q21-22 and 3p21, have been shown to be involved in the development of certain tumors (see Jiang, 1996; Schlosshauer et al., 2002) and reduced expressions of both alpha- and beta-catenin have been described in various tumors including breast carcinoma (Hashizume et al, 1996). Besides adhesion functions, beta-catenin binds to the tumor suppressor gene APC. APC mutation disturbs the equilibrium and cytoplasmic levels of free beta-catenin level in the cell and may have a role in tumorigenesis.