  Cells coexist together in colonies or as tissues. Their behaviour is
controlled by an interplay between intercellular forces and biochemical
regulation. We develop a simple model of the cell cycle, the fundamental
regulatory network controlling growth and division, and couple this to the
physical forces arising within the cell collective. We analyse this model using
both particle-based computer simulations and a continuum theory. We focus on 2D
colonies confined in a channel. These develop moving growth fronts of dividing
cells with quiescent cells in the interior. The profile and speed of these
fronts are non-trivially related to the substrate friction and the cell cycle
parameters, providing a possible approach to measure such parameters in
experiments.
