Matrix-assisted laser desorption ionization-time of flight analysis and examination of protein profiles from the SwissProt database revealed that the previously defined p97 repressor is ZNF224, a zinc finger protein. ZNF224, a Kruppel-like zinc finger transcription factor, is the repressor protein that specifically binds to the negative cis-element AldA-NRE and affects the AldA-NRE-mediated transcription.