GZMB and neoplasm: Other suppressive mechanisms in regard to Tregs’ roles are: the secretion of suppressive cytokines such as IL-10, TGF-β, killing activated CD8+, utilizing Neuropilin/semaphorin-4a pathway (197), the consumption of available IL-2 and releasing GrB, exosome production and delivery of the pTreg products to effector T cells, diminishing anti-tumor immunity (86, 197).