One way scientists are manipulating the body’s natural defenses is called adoptive cell transfer, which involves extracting a patient’s own T-cells, genetically modifying them to target the specific proteins that mark cancer cells, and then injecting them back into the patient. While this kind of therapy is proving effective against some cancers, it’s not as effective targeting cancers with solid tumors. That could soon change thanks to the discovery of a new protein that helps direct our cancer-fighting T-cells to go attack tumors.