Signal transduction without signal: Receptor clusters can direct cell movement

Whether we smell, taste or see, or when adrenaline rushes through our veins, all of these signals are received by our cells via a specific group of receptor proteins called G protein-coupled receptors, which transmit signals to the inside of the cell. Biochemists have now discovered that such receptors can also produce signals even in the absence of an external stimulus: For certain receptors clustering is apparently sufficient.

from Latest Science News -- ScienceDaily https://www.sciencedaily.com/releases/2021/02/210225190945.htm