RBP4 Antibody Host:Rabbit Antibody Type:Polyclonal Species Reactivity:Human Application:Western blot Western blotting (1:500-1:1000). However, the optimal concentrations should be determined individually. Recombinant human RBP4 can be used as a positive control. The antibody recognizes ~25 kDa human RBP4. Reactivity to other species has not been tested.