A majority of suppliers have reported the clone 4C4.9 to be a mouse monoclonal antibody specific to the human gene, S100A1, or S100 calcium binding protein A1. Other suppliers describe clone 4C4.9 to be a mouse monoclonal antibody against human S100B, or S100 calcium binding protein B. Suppliers have reported additional species reactivites for the target of this clone, including bovine, mouse and rat. Indicated applications for antibody clone 4C4.9 include Western blot, immunohistochemistry, flow cytometry, immunofluorescence, and immunocytochemistry.