Cancer can result from the loss of cell-cell interaction.  In normal cells, growth is controlled by contact inhibition in which contact with neighboring cells causes a stunt in cell growth. Contact inhibition is thought to be mediated by cadherins, proteins that play an important role in cell adhesion. This inhibition prevents cells from piling up on top of one another and forming mounds.  However, in cancerous cells where expression of E-cadherin is lost, contact inhibition is lost and results in uncontrolled growth or proliferation, tumor formation, and metastasis.