A dysfunctional immune system significantly contributes to the development of cancer. Several therapeutic strategies to activate the immune system to target cancer cells have been approved to treat different types of cancer, including melanoma. However, some patients do not show beneficial clinical responses to these novel and very promising immunotherapies. In a new article published in Proceedings of the National Academy of Sciences of the United States of America, Moffitt Cancer Center researchers demonstrate how an important defect in STING gene expression in melanoma cells contributes to their evasion from immune cell detection and destruction.