Beta-catenin and ZO-1: shuttle molecules involved in tumor invasion-associated epithelial-mesenchymal transition processes.

The cytoplasmic/nuclear relocalization of beta-catenin and ZO-1 from the adherens and tight junctions are common processes of the epithelial-mesenchymal transition (EMT) associated with tumor invasion. Data are now accumulating to demonstrate that these molecules, which shuttle between the plasma membrane and the nucleus or the cytosol, are involved in signaling pathways, and contribute to the regulation of genes such as vimentin or matrix metalloproteinase-14 which are turned on during EMT.