IFNGR1 and autoimmune disease: Library A was then applied to the RaPID selection against IFNGR1,a receptor of IFN-γ known as a proinflammatory cytokine.54,55 An inhibitor of the IFN-γ and IFNGR1 protein–proteininteraction (PPI) would be a therapeutic agent for autoimmune diseases.The random mRNA library was translated into the peptide library, followedby conjugation of the peptide with the parent mRNA via a puromycinlinker (SI Figure S3A).