FIGURE 20-3 Model for the generation of cell-cell adhesions. Lateral interactions between cell-adhesion molecules (CAMs) within the plasma membrane of a cell can form clusters of monomers (left). The parts of the molecules that participate in these cis interactions vary among the different CAMs. Trans interactions between domains of CAMs on adjacent cells generate a strong, Velcro-like adhesion between the cells. The models shown here are based on CAMs called cadherins. See M. S. Steinberg and P. M. McNutt, 1999, Curr. Opin. Cell Biol. 11:554 and J. Brasch, O. J. Harrison, B. Honig, and L. Shapiro, 2012, Trends Cell Biol. 22:299–310.