One promising approach in the fight against cancer is to activate the immune system to detect and fight tumor cells. However, cancer cells have evolved many ways of protecting themselves from the immune system: For example, they hide within the tumor stroma or surround themselves with a cloud of inhibitory signals that inhibits the activity of infiltrating immune cells. In this project, we want to uncover the complex relationship between changes in the tumor stroma and the presentation of antigens on the surface of tumor cells in models of colorectal cancer. Therefore, our lab uses genetically modified tumor organoids, i.e. small units of tumor cells, for immunological studies.