IRF7 and neoplasm: Other mechanisms by which MDSCs mediate immune suppression within the tumor and inflammatory microenvironment include exosomal S100A9 via the RAGE and toll-like receptor (TLR)4 signaling pathways [120], the interferon regulatory factor 7 (IRF7) [121], and exosomal prostaglandin E2 by enhancing IL-10+ B Cells [122].