PRDX4 is an antioxidant enzyme that is part of the peroxiredoxin family. PRDX4 is localized to the cytoplasm. PRDX4 reduces hydrogen peroxide and alkyl hydroperoxides to water and alcohol with the use of reducing equivalents derived from thiol-containing donor molecules. PRDX4 has a regulatory part in the activation of the transcription factor NF-kappaB. PRDX4 participates in redox regulation of the cell. PRDX4 regulates the activation of NF-kappa-B in the cytosol by a modulation of I-kappa-B-alpha phosphorylation.