EXPERIMENTAL FIGURE 20-12E-cadherin mediates Ca2+-dependent adhesion of L cells. Under standard cell culture conditions, in the presence of calcium in the extracellular fluid, L cells do not aggregate into sheets (left). Introduction of a gene that causes the expression of E-cadherin in these cells results in their aggregation into epithelium-like clumps in the presence of calcium (center), but not in its absence (right). Bar, 60 µm.