Fig. 1From: Potential anti-tumor effects of regulatory T cells in the tumor microenvironment: a reviewThree subgroups can be identified based on phenotype and function of Tregs. Stable Tregs: express FoxP3, have immunosuppressive function; Unstable Tregs: express low or no FoxP3 that secrete IFN-γ and can promote anti-tumor immunity; Fragile Tregs: express FoxP3 while secreting IFN-γ, and have anti-tumor activity [30]Back to article page