Fig. 2. Integrins orient the cell-division axis. (A) The mitotic spindle aligns along the long axis of the cell, which lies at right angles to the plane of cytokinesis. A mitotic cell is shown, and the microtubule connections between the cell edge (cortex, plasma membrane) and spindle poles, and between the spindle poles and chromosomes (which accumulate at the metaphase plate) are highlighted. (B) Cells adhere to the ECM through integrins. They can either divide along the plane of the ECM (turquoise in panels C-E) to which they adhere (x- or y-axes), or away from it (z-axis). (C,D) Tension provided along the x-axis causes unilateral extension (C), which becomes bilateral if tension is also provided in the y-axis (D), forming a sheet of cells. (E) Orientation of the plane of division along the z-axis causes cells to become displaced away from the initial ECM. These new (purple) cells have a microenvironment that is different to the parental (pink) cells. Thus, following cell division, daughter cells become located either in a similar niche to their parents, or in a new microenvironment.