To access the data, click or select the words “Appendix 4.” Confluent cultures of Caco-2 cells were immunolabeled with the rabbit anti-NHS and anti-tircelllin antibody, as indicated. The epithelial cell specific isoform of NHS, NHS-A, localizes to the cell periphery in polarized epithelial cells where it interacts with the tight junction protein ZO-1 [33]. Peripheral immuno-positive labeling in Caco-2 cells with the anti-NHS antibody indicates their epithelial characteristic and polarization in culture (left panel). Tricellulin, a tricellular tight junction protein, localizes to tricellular tight junctions and bicellular junctions in epithelial cells [40]. Intense immune-positive labeling with anti-tricellulin antibody in Caco-2 cells at sites where three cells meet (tricellular tight junctions) and positive labeling at sites where two cells meet (bicellular tight junctions) also demonstrate their polarised epithelial characteristic (right panel).