Kyoto University researchers have engineered a synthetic protein named Crunch that reprograms the phagocytic immune system to selectively eliminate living harmful cells, such as cancer or overactive immune cells. Crunch modifies the natural Protein S 'eat-me' signal to recognize targeted cell surface markers, facilitating their engulfment by phagocytes and promoting tissue repair. This represents a pioneering strategy to harness and direct the body’s innate clearance mechanisms for therapeutic benefit.