ight junctions (TJs) are cell-ceil adhesion belts that encircle epithelial and endothelial cells at the limit between the apical and the lateral Tmembrane. These junctions are crucial for the establishment of separate compartments in multicellular organisms and for the exchange of substances between the internal milieu and the external environment. The perception of TJs has changed over the years. From being regarded as static paracellular seals, they have come to be perceived as dynamic structures that adjust their morphol ogy and function in response to physiological, pharmacological and...