FOXP3 and neoplasm: PtenΔ/ΔBRF1Tg tumours contained significantly fewer stromal CD3 and CD4 T cells (p = 0.0438, 0.0394, respectively) but stromal CD8 or FOXP3 (a marker for regulatory T cells) T cells were not altered (Figs. 3g–i, S5d, c).