FOXP3 and neoplasm: Immunohistochemistry corroborated the cytofluorimetric data by detecting an expansion of Foxp3+ cells, mostly distributed in the T cell areas, in the spleen of tumor-bearing WT mice (18.8 ± 4.3%) versus both healthy WT (7.1 ± 4.2%) and KO (7.5 ± 3.6%) mice and versus tumor-bearing IL-30KO mice (9.2 ± 4.0%) (Tukey’s HSD test: p < 0.01), regardless of IL-30 silencing in the implanted tumor cells (Fig. 4F).