Cancer cells can weaken the immune system by producing a protein that prevents its most important defenders from attacking. TRAILshort stops T cells, the immune system’s main cancer-fighting cells, from recognizing and destroying cancerous and virus-infected cells. They discovered in 2020 that cancer cells also produce the protein, but the process by which it suppressed T cell activity remained unexplained. Researchers suggest that it could offer a more selective way to reduce harmful immune activity in autoimmune diseases or transplantation without suppressing the entire immune system. “By targeting TRAILshort, we may be able to strengthen immune responses against cancer and chronic infections or, in other diseases, reduce harmful immune activity.”