S100A9 and metastatic malignant neoplasm in the lymph nodes: We found that both MDSCs and S100A9 are correlated to Dukes staging and lymph node metastasis, and activation of the RAGE-mediated p38 MAPK and TLR4-mediated NF-κB signaling pathways are involved in S100A9-induced trafficking and activation of MDSCs, respectively.