Signal transduction by the peptide which mimics the activity of thrombopoietin

Thrombopoietin (TPO) plays a central role in megakaryopoiesis and platelet production. It is a ligand for c‐mpl, which is a member of the hematopoietic receptor superfamily. We have recently identified several human c‐mpl binding peptides which are distinct from TPO, from phage random peptide libraries. PK1M is one of these peptides and is an agonist of c‐mpl which is TPO receptor. We show here that PK1M induces the tyrosine phosphorylation of the Janus kinase 2 (JAK2) and the activation of the signal transducer and activation of transcription 5 (STAT5) in TPO‐dependent cells like TPO.