E-cadherin-mediated adhesion is not the founding event of epithelial cell polarity in Drosophila.

Formation of a polarized epithelial layer is a fundamental step during the development of multicellular animals. This process involves the coordinated action of adhesion molecules, actin remodeling and spatial organization of membrane traffic. A recent article describes a new hierarchy for the development of epithelial polarity in the early Drosophila embryo. Bazooka, a Par-3 homolog, is properly localized in the absence of adherens junctions, indicating that the formation of epithelial junctions is not the founding event of epithelial polarization.