The signal transduction of type III IFNs depends on the IFN-λ-specific receptor, IL-28Ra chain and IL-10R2 chain [161,165]. Synthetic IFN-λ binds to IL-28Rα and induces a conformational change within the receptor subunits, that triggers the activation of the receptor-associated tyrosine kinases (TYK2 and JAK1), which then phosphorylate STAT1 and STAT2. STAT1 and STAT2 are heterodimerized and interact with IRF9 to form the ISGF3 transcription complex that binds to ISRE in the promoters of ISGs, to induce the expression of hundreds of proteins with antiviral functions [166].