The immune system protects the body from cancer. To protect healthy body cells from its own immune system, they have developed a protective shield: the protein CD47 is a so called ‚don’t eat me‘ signal, which tells the immune cells to stand back. Tumor cells exploit this CD47-based protection strategy for evading the immune system, by increasing presentation of CD47 on their cell surface. A team has now developed a therapy concept for programming the tumor cells to produce on their own a CD47-blocking and immune-activation fusion protein. This therapy approach could stop tumor growth.