The body’s cells respond to stress—toxins, mutations, starvation or other assaults—by pausing normal functions to focus on conserving energy, repairing damaged components and boosting defenses.

If the stress is manageable, cells resume normal activity; if not, they self-destruct.

Scientists have believed for decades this response happens as a linear chain of events: sensors in the cell “sound an alarm” and modify a key protein, which then changes a second protein that slows or shuts down the cell’s normal function.