IRF3 and neoplasm: The activation of intrinsic RIG-I in tumor cells induces MHC-I expression, thereby promoting CD8+ T cell-mediated recognition and killing.502,507 In human melanoma, RIG-I activation enhances MHC-I expression primarily through two pathways: IFNβ-mediated intrinsic expression and an IFN-independent IRF1 and IRF3 salvage pathway.507