Intercellular junctions and cell-matrix adhesions play important roles in the maintenance of epithelial integrity. Assembly and remodeling of the plasma membrane complexes are regulated by membrane trafficking and fusion. This thesis is aimed to elucidate the roles of an important membrane fusion protein, Ykt6, in the regulation of epithelial cell adhesion and migration. For the first time, we show that Ykt6 is essential for assembly of adherens junctions and tight junctions in human prostate epithelial cells. We also observed that Ykt6 negatively regulates both collective epithelial cell migration and cell invasion into Matrigel. The effects of YKT6 on epithelial junctions involves expressional regulation of key junctional proteins, E-cadherin and claudin-4, whereas its effects on cell motility can be explained by antagonizing functions of junctional adhesion molecule-A. Overall, this study identifies YKT6 as a novel regulator of epithelial cell adhesions and motility.