TNF and neoplasm: In the second phase, IMCs are converted into MDSCs in peripheral tissues mainly due to the action of pro-inflammatory cytokines from tumor-associated stromal cells and activated immune cells, such as TNF-α, multiple ILs, PGE2, COX2, and involves signaling pathways, including NF-κB, STAT1, STAT6, and ER stress pathways [196, 197].