IRF1: ProductsInterferon regulator transcription factors (IRF) are a family characterized by a helix-turn-helix DNA binding domain enriched in tryptophan repeats. IRF family members show diverse cellular regulation of interferon-stimulated gene transcription, viral-mediated gene activation, apoptosis, differentiation, and cellular growth. IRF1 knock out mice show defects in NK and T cell function, as well as, develop CD30+ lymphoproliferative disease. IRF2 functions as a regulator of type I interferons influencing cellular proliferation and immune response through transcriptional regulation. IRF2 competitively inhibits IRF1 gene activation, as well as, stimulating transcription on its own. Human IRF3 is a transcription factor that binds the interferon-sensitive response element (ISRE) and is activated by Toll-like receptors, TLR3 and TLR4.