While other members of this family, such as S100A4 [28, 29], S100A7 [30] and S100A13 [31], have been shown to participate under similar conditions, this discussion focuses on S100A8/A9's role in tumorigenesis by reviewing the effects of S100A8/A9 on tumor cells or vascular endothelial cells. The gene discussed is S100A4; the disease is neoplasm.