Monoclonal anti-Parvalbumin is a mouse IgG1 produced by hybridization of mouse myeloma cells with spleen cells from mice immunized with parvalbumin purified from carp muscles (1). The antibody was evaluated for specificity and potency: a) by indirect immunofluorescent or immunoperoxidase labeling as well as Avidin-Biotin staining of cryostat or vibratome-sections of 4% paraformaldehyde fixed tissue; b) by immunoenzymatic labelling of immunoblots; c) by radioimmunoassay (RIA)(1). The product is a monoclonal antibody (McAB) against parvalbumin, a calcium-binding protein of the EF-hand family related to calmodulin and troponin-C. The antibody reacts specifically with parvalbumin in tissue originating from human, monkey, rabbit, rat, mouse chicken and fish. The McAB specifically stains the 45Ca-binding spot of parvalbumin (MW 12'000 and IEF 4.9) in a two-dimensional "immunoblot". In a RIA set up the McAB measures parvalbumin with a sensitivity of 10 ng/assay and an affinity of 7.9 x 1012 L/M (1).