A living cell is exposed to a variety of stimuli. Countless messengers dock on its surface, where receptors in the cell membrane receive the incoming "orders." Signaling cascades are then triggered inside the cell, which ultimately responds by producing or breaking down substances, or by switching genes on and off in the cell nucleus. So far so clear. But what's exactly going on here? Researchers at the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC) have now discovered that the processes are far more complex than previously thought. Andreas Bock is the co-last author of the study that has been published in the journal Cell and recently headed the Receptor Signaling Lab at the MDC. He is now a professor at Leipzig University.