Abstract: Cell adhesion plays pivotal roles in the morphogenesis of multicellular organisms. Epithelial cells form several types of cell-to-cell adhesion, including zonula occludens (tight junctions), zonula adhaerens (adherens junctions), and macula adhaerens (desmosomes). Although these adhesion complexes are basically observed only in epithelial cells, cadherins, which are the major cell adhesion molecules of adherens junctions, are expressed in both epithelial and non-epithelial tissues, including neural tissues (Kawauchi, 2012). The cadherin superfamily consists of more than 100 members, but classic cadherins, such as E-cadherin (Cdh1), N-cadherin (Cdh2), and R-cadherin (Cdh4), amount to about 20 members. Classic cadherins are single transmembrane proteins, which basically exhibit homophilic adhesion in an extracellular Ca2+-dependent manner. The cell adhesion activity is also regulated intracellularly. The intracellular domain of classic cadherins binds to β-catenin, which interacts with α-catenin (Figure 1). Because α-catenin binds to an actin-binding protein, vinculin, the catenin complex mediates the interaction between classic cadherins and the actin cytoskeleton, which stabilizes cell-to-cell adhesion (Kawauchi, 2012).