Aresearch team needs an antibody that binds to a human protein of interest so that protein expression can be monitored. they use epitope tagging, adding a sequence of amino acids called an epitope to the protein through dna recombination. in this way, they do not need to develop an antibody to the protein, but can use a known, commercially available epitope‑specific antibody. however, they are unable to localize the protein using the epitope‑specific antibody. why did the antibody fail to indicate protein localization? the antibody is removed during rna processing. the antigen‑binding site does not recognize the antibody. the commercial antibodies the team used were developed from rat tissues. only the proenzyme contains the added epitope, which is disrupted during activation.