FOXP3 and renal cell carcinoma: Next, we investigated Treg and MDSC expression in orthotopic and metastatic lung tumors by immunofluorescence staining, which confirmed the presence of Gr-1+ CD11b+ MDSCs (Figure 5C) and CD4+ Foxp3+ Tregs (Figure 6C) in RCC metastatic lung tumor tissues following treatment with the combination of YM155 and IL-2.