For example, upon recruitment to the tumour site MDSCs could also promote tumour growth and metastasis by secreting the inflammatory proteins S100 calcium-binding protein A8/A9 (S100A8/A9) which mediate the activation of mitogen-activated protein kinase (MAPK) and NF-κB signalling pathways in tumour cells [90–92]. Here, S100A8 is linked to neoplasm.