Recombinant IL29 is a bioactive protein intended for use in cell culture applications. IL29 is functionally similar to type I interferons, including antiviral activity and up-regulation of MHC class I antigen expression. IL29 signal through the same heterodimeric receptor complex that is composed of the IL-10 receptor b (IL-10 Rb) and a novel IL-28 receptor a (IL-28 Ra, also known as IFN-γ R1). Binding to the receptor complex induces Jak kinase activation, as well as STAT1 and STAT2 tyrosine phosphorylation.