(1) Stable Tregs: express FoxP3, Nrp1, and Helios, exhibit immunosuppressive function, and are the predominant subgroup of Tregs; (2) Unstable Tregs: low or no expression of FoxP3 and secretion of IFN-γ, supporting anti-tumor immune responses; (3) Fragile Tregs: express FoxP3 and secrete IFN-γ, contributing to anti-tumor effects [30] (Fig. 1). Here, NRP1 is linked to neoplasm.