FOXP3 and neoplasm: CD4+FoxP3+ Tregs were associated with a bad prognosis in the TME (P = 0.044) (Additional file 1: Figure S4H), as well as CD4+FoxP3+ Tregs surrounding S15− tumor cells (P = 0.035) (Fig. 6E), and S15+ tumor cells (P = 0.008) (Fig. 6F).