Fig. 2.

Mechanical cell competition scenarios driven by boundary conditions.

A: Left: Cell compaction driven by active corralling: the convergent collective migration of the green population (WT) toward the purple population (here scribble^−/− mutant cells) induces cell compaction and cell death. Adapted from [24]. Right: Evolution of cell number of the two populations over time during competition (adapted from [24,43]). B: Spontaneous compaction and cell elimination driven by local topological defects [58]. The red lines show the main local alignment of MDCK cells (behaving like a nematic liquid crystal). The red cell is the dying cell at the tip of the so called “comet like” topological defect. C: Cell compaction and cell elimination driven by clone boundary line tension [62]. Cell misspecification (here induction of an oncogene) leads to the accumulation of acto-myosin at clone boundary (red thick line). The high line tension increases pressure within the clone (see formula) and is higher for small clone radius. The high pressure drives cell elimination until the clone disappear. The same process can either eliminate pretumoural cells if they occupy a small portion of the tissue (top) or induce WT cell elimination (bottom) if the pretumoural cells occupy the majority of the tissue.