  The mechanisms driving the collective movement of cells remain poorly
understood. To contribute toward resolving this mystery, a model was formulated
to theoretically explore the possible functions of polarized cell-cell adhesion
in collective cell migration. The model consists of an amoeba cell with
polarized cell-cell adhesion, which is controlled by positive feedback with
cell motion. This model cell has no persistent propulsion, and therefore
exhibits a simple random walk when in isolation. However, at high density,
these cells acquire collective propulsion and form ordered movement. This
result suggests that cell-cell adhesion has a potential function, which induces
collective propulsion with persistence.
