“…This has become a popular continuum description of cell adhesion, with a number of variations proposed to study tumour invasion and cell movement across the ECM [15,22,25,37,43,79,100], development and cell-sorting dynamics [8,23,43,80]. Attention has also been given over the years to variations of the nonlocal modelling of adhesion by considering di↵erent ways to enforce limits on the cell density and furthermore to include nonlinear cross di↵usion, that is substituting linear di↵usion modelling random movement with nonlinear di↵usion modelling movement of cells down a density-dependent pressure gradient, into the overall model, see [21,23,63,72]. The principal e↵ect of these modifications is that they lead to sharper interfaces between the densities of di↵erent cell types or the ECM or can even lead to strict segregation of them.…”