Importantly, we observed a significant enrichment of the immunosuppressive CD4+FoxP3+ Treg population in the primary tumours of JL mice and consequent elevation of Treg/CD8 ratio (Fig. 5f), which together with CD4/CD8 ratio is a prognostic indicator of therapy responsiveness and survival in breast cancer patients32–34. Here, FOXP3 is linked to breast cancer.