ABSTRACT
Epithelial cells usually form tightly connected sheets of monolayers, which occurs as a result of the subcellular distribution of cadherins, specific integrins, cell-cell junctions (desmosomes, tight junctions, adherens junctions, and gap junctions), as well as the polarized organization of the cytoskeleton. This organization establishes an apical-basal polarity through their association with a basement membrane, which, under normal circumstances, allows cells to move laterally within the epithelial layer (Birchmeier, Birchmeier, and Brand-Saberi 1996) but prevents their entrance into the underlying extracellular matrix (ECM).
