The cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), also known as CD152, is a member of the immunoglobulin superfamily that is expressed by activated T cells and transmits an inhibitory signal to T cells (1,2). Both it and the homologous T-cell co-stimulatory protein CD28 bind to CD80 (B7-H1) and CD86 (B7-H2) on antigen-presenting cells (APCs) (3). Mutations in the CTLA-4 gene have been implicated in multiple autoimmune diseases (4). CTLA-4 also functions as an immune checkpoint protein, and anti- CTLA-4 antibodies have been successfully used in the treatment of cancer (5).ProSci's Risk-FreeTM antibodies are mouse monoclonal antibodies made to improve in vivo studies. Unlike antibodies developed using proteins made in yeast or bacteria, Risk-FreeTM antibodies are developed with antigens expressed in mammalian cell lines, giving the most native post-translational modifications to the protein. Validated for flow cytometry and ELISA Rigorously tested for the following applications: Immunoblot Immunohistochemistry Immunocytochemistry Immunofluorescence Multiple antibodies per target allowing the user to choose the best antibody for their application Available individually or as a set Risk-FreeTM means they are guaranteed to work for their approved applications