Whether moving around or interacting with their neighbours, the cells in our tissues are ever dynamic, and this affects the surrounding environment. The mechanical forces they exert can be studied by watching cells under the microscope as they move along a gel containing minute fluorescent beads. Movement displaces the beads, allowing measurements of the traction stress [force imposed on an area], generated by the cell. Pictured is a mouse embryo cell expressing a fluorescent form of a protein (shown in white) that links the cytoskeleton – the network of protein fibres that gives cells their shape – to the cell membrane. The magnitude of stress is colour-coded by the fluorescing beads, with warmer colours indicating higher values. High levels of stress are found at protruding edges where the protein clusters and the cell comes into contact with the gel – transforming cellular activity into movement.
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