Figure 2.

Topological interactions between front cells and followers. The upper panel represents a top-view and the lower panel a side-view of the same region—the front part of a migrating cohort. As the substrate (ECM) is at the bottom, it is accessible to all migrating cells in the case of a simple monolayer. Cell 1 has one free edge (red) and three bound edges (orange and yellow) giving inherent anisotropy. The bound edges might also be under contact-dependent tension. Cell 2 has only bound edges, but they might experience different amounts and types of stress, for example due to pull from cell 1, and traction and resistance in other cells. The yellow edges might experience polarized shear stress. ECM, extracellular matrix.