According to the literature, this antibody recognizes human perforin, a 70 kD cytolytic protein found in cytolytic granules of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. Perforin is one of the primary mediators of target cell lysis by CTLs and NK cells. In the presence of calcium, perforin forms pores in the membranes of target cells, leading to cell death. The δG9 antibody also reacts with bovine, but not mouse, perforin.