Description: The Clone 9 monoclonal antibody reacts with mouse B7S1, also known as B7H4. B7S1 is a newly discovered member of the B7 family. It is speculated that the costimulatory regulation of T cells by B7S1 is influenced by the activation status of B cells. The ligand for B7S1 has not been identified yet. This antibody is not blocking. Simultaneous double staining of cells with two anti-mouse B7-H4 antibodies, Clone 9 and 188, suggests that epitopes recognized by these mAbs are different and/or there is no steric hindrance when antibodies are used together.