E-cadherin molecules span the membranes of epithelial cells and hook into E-cadherin molecules on adjacent cells. E-cadherin also projects into the cell's interior and hooks into the proteinacious skeleton, called the cytoskeleton, which supports the cellular structure. 

E-cadherin links with actin molecules in the cytoskeleton via a set of molecules called catenins. Epithelial cells are also molecularly connected with collagen and other proteins in the basal lamina.

Integrins spanning the epithelial-cell membrane bind with fibronectin, which in turn binds with collagen in the basal lamina. Like E-cadherin, integrin molecules also project into the epithelial-cell interior and bind with actin in the cytoskeleton.

Before cancer cells can spread to foreign organs, they must break all of these bonds.