IRF3 is a member of the interferon regulatory transcription factor (IRF) family. IRF3 plays an important role in the innate immune system's response to viral infection. It is found in an inactive cytoplasmic form that upon serine/threonine phosphorylation forms a complex with CREBBP. The complex translocates into the nucleus for the transcriptional activation of interferons alpha and beta, and further interferon-induced genes.