Highly simplified diagram showing the signaling network between the inflammation and metastasis. Cancer cell in primary tumors are surrounded by numerous cells including fibroblasts, macrophages, myeloid-derived suppressors cells (MDSC) and neutrophils. These inflammatory cells produce pro-inflammatory factors, such as hypoxia, TGF-β, TNF-α, IL-6 and IL-1. These inflammatory factors activate NF-κB and STAT3 to induce epithelial-to-mesenchymal transition (EMT) and tumor metastasis through regulation the expression of transcription factors and proteases.