Tohoku University scientists have, for the first time, provided experimental evidence that cell stickiness helps them stay sorted within correct compartments during development. How tightly cells clump together, known as cell adhesion, appears to be enabled by a protein better known for its role in the immune system. The findings were detailed in the journal Nature Communications. Scientists have long observed that not-yet-specialised cells move in a way that ensures that cell groups destined for a specific tissue stay together. In 1964, American biologist Malcolm Steinberg proposed that cells with similar adhesiveness move to come in contact with each other to minimise energy use, producing a thermodynamically stable structure. This is known as the differential adhesion hypothesis.