E-cadherin and the associated catenin complex have been recognised as performing a key role in cell adhesion. Loss of cell adhesion is seen as a key step in the cascade leading to tumour metastasis. The ability of both extra- and intracellular factors to regulate E-cadherin-mediated cell adhesion in physiological processes has provided insight into both the interactions of the E-cadherin–catenin complex, and possible mechanisms utilised by tumours in the process of metastasis. The interaction of the E-cadherin–catenin complex with various regulating factors, their effect on cell signalling pathways, and the relationship with the metastatic potential of tumours are reviewed.