Occludin is present in tight junctions of epithelial and endothelial cells as well as in non-epithelial cells such as neurons, astrocytes, oligodendrocytes, lymphocytes, monocytes, denritic cells & osteoblasts.  Being a homophilic molecule, occludin is likely to be involved in polarized trafficking & cell-cell interactions in both epithelial and non-epithelial cells.