S100A9 and neoplasm: Indeed, estrogen induces neutrophil expression of a plethora of genes encoding protumoral cytokines/chemokines(e.g. CXCL1, CXCL2, S100A8, S100A9), matrix metalloproteinases(MMP3, MMP9) and COX-2 that are all known to promote tumor growth and metastasis28.