Emerging Role for Epithelial Polarity Proteins of the Crumbs Family as Potential Tumor Suppressors

Figure 1

Organization of epithelial tissues. Epithelial cells are polarized along an apical-basal axis. The apical domain faces a lumen or the environment, the lateral domain contacts neighboring cells, and the basal domain is anchored to the basement membrane. This polarized architecture sustains unidirectional functions, such as vectorial transport. The apical and lateral domains are segregated by the zonula adherens, which is a circumferential adherens junction maintaining intercellular adhesion within epithelial tissues. In chordates epithelia, paracellular diffusion is limited by tight junctions, which sit apical to the zonula adherens. In insect, this sealing function is assumed by septate junctions that are established basal to the zonula adherens.