TGFB1 and neoplasm: Moreover, CD8+ T lymphocytes from anti-PD-1-treated B16F10E-KO, but not from B16F10E, displayed increased percentages of Ki-67+ cells as compared to isotype-treated B16F10E-KO suggesting that PD-1 blockade promoted CD8+ T cell expansion in the former tumours associated with decreased TGF-β activation (Fig. 5e).