The monoclonal antibody clone 1E2 recognizes S100A4. S100A4 is a member of the S100 family. To date, the family consists of 22 members. S100 proteins are low molecular weight calcium binding proteins. The proteins consist of 2 calcium binding EF-hands located on the termini flanked by hydrophobic hinge regions. Calcium ions acts as a global second messenger involved in the regulation of many aspects of cell function. S100 proteins are involved in sensing and transforming calcium signals to downstream cellular responses. S100 proteins are located in the cytoplasm and/or nucleus of a wide range of cell types and involved in the regulation of cellular processes such as cell cycle progression and differentiation and inflammatory responses. Several S100 members have been found to act as cytokines in inflammation, particularly in autoimmune skin conditions such as psoriasis. S100A4 may function in motility, invasion, and tubulin polymerization. Chromosomal rearrangements and altered S100A4 gene expression have been implicated in tumor metastasis. Studies have shown that S100A4 is involved tumor progression and metastasis in various malignant tumors. Detection of S100A4 expression becomes a promising candidate biomarker in cancer early diagnosis and prediction of cancer metastasis. Therefore S100A4 may have high therapeutic value.