When a tumor develops, it creates a structure around itself called the tumor stroma, within which blood and lymphatic vessels ensure nutritional and respiratory biological exchanges. Lymphangiogenesis, i.e. the development of lymphatic vessels, is generally associated with a poor prognosis, as it favours the spread of metastases to other organs. By studying the cells that make up the wall of lymphatic vessels, a team from the University of Geneva (UNIGE) has made an unexpected discovery: an enzyme they express appears to play a key role in supporting immune cells, particularly when they are activated by anti-tumor treatments. These results, published in Nature Communications, could pave the way for improving the effectiveness of immunotherapies.