Reinforcing suppression using regulators: a new link between STAT3, IL-23, and Tregs in tumor immunosuppression.

STAT3 plays many roles in tumorigenesis. In this issue of Cancer Cell, Kortylewski et al. show that in the tumor microenvironment, STAT3 enhances the expression of the protumor cytokine IL-23 in macrophages but inhibits the antitumor cytokine IL-12 in dendritic cells. STAT3 also mediates IL-23's effect of activating tumor-infiltrating regulatory T cells.