Two of the most advanced drugs developed by screening phage-displayed libraries of random peptides are the EpoR [47] and TpoR [48] peptide agonists that target the erythropoietin and thrombopoietin receptors for the treatment of anemia and idiopathic thrombocytopenic purpura respectively. The gene discussed is MPL; the disease is autoimmune thrombocytopenic purpura.