IRF-3 is a member of the interferon regulatory transcription factor (IRF) family. It mediates interferon-stimulated response element (ISRE) promoter activation and functions as a molecular switch for antiviral activity. DsRNA generated during the course of a viral infection leads to IRF-3 phosphorylation on the C-terminal serine/threonine cluster. This induces a conformational change, leading to its dimerization, nuclear localization and association with CREB protein binding to dsRNA-activated factor 1, a complex which activates the transcription of genes under control of ISRE. The phosphorylated IRF-3 is under negative regulation by ubiquitin-mediated degradation. Recent research indicates that it plays a critical role in stimulated TLR-mediated IL-27 P28 gene expression.