DNA-binding transcription factor that specifically binds to the upstream regulatory region of type I interferon (IFN) and IFN- inducible genes and regulates their expression (PubMed:39013473, PubMed:7687740). Mainly acts as a transcription repressor, repressing expression (PubMed:39013473). Also acts as an activator for several genes including H4 and IL7 (PubMed:15226432, PubMed:9540062). Constitutively binds to the ISRE promoter to activate IL7 (PubMed:15226432). Involved in cell cycle regulation through binding the site II (HiNF-M) promoter region of H4 and activating transcription during cell growth (PubMed:9540062). Antagonizes IRF1 transcriptional activation (By similarity). {ECO:0000250|UniProtKB:P23906, ECO:0000269|PubMed:15226432, ECO:0000269|PubMed:39013473, ECO:0000269|PubMed:7687740, ECO:0000269|PubMed:9540062}. [Isoform 2]: Unable to bind to IRF2BP1 and IRF2BP2 corepressors and cannot mediate repression. . This is the function of Ensembl gene identifier ENSG00000168310 (IRF2, interferon regulatory factor 2).