TGFB1 and neoplasm: TGF-β also alters the polarization of the CD8+ cells in tumor-bearing mice, resulting in elevated interleukin 17 (IL-17), which suppressed apoptosis of tumor cells.(18) TGF-β, coordinated with IL-21, induces CD4+CD25+ regulatory T cells that counterbalance the effect of IL-6 that promotes proinflammatory IL-17-producing T cells.(19) In addition, TGF-β is responsible for CD4+CD25+ regulatory T-cell inhibition of NK cell functions.(20)