A cell's grip on its surroundings can suddenly jump between two distinct strengths.

To move around, cells pull on the mesh of molecules surrounding them, called the extracellular matrix. This pulling creates a loop. The mesh gets stiffer as it stretches, so a cell pulling on it makes it stiffer. At the same time, cells pull harder when their surroundings are stiffer. Researchers studied this feedback loop using mathematical theory. They discovered it can cause two steady states to exist, a behavior called bistability, along with memory effects known as hysteresis. Because of this, gradually ramping up the cell's pulling strength or the mesh's stiffening behavior causes a sudden jump from low to high pulling forces. This abrupt shift may spark collective cell movement during growth or tumor progression, while keeping cell pulling steady in patchy environments.

Why it matters

When cells crawl through the body, they need to pull on their environment. This work shows that this pull can abruptly switch from weak to strong, like a light switch. That switch might help explain how groups of cells suddenly start migrating during embryo development or cancer spread. It also suggests that cells can maintain steady traction even when their surroundings vary in stiffness.

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