Western blotting can show qualitative changes in the relative abundance of individual proteins. Via addition of quantitation standards to the Western blot samples the absolute amounts of a protein in a given sample can be evaluated. Using a dilution range of protein standards a concentration curve can be established that allows the measurement of concentrations of unknown protein samples. Quantitation standards for plant research can be found here: anti-Cp47 (Psbb) antibody und anti-Atpb protein antibody.