IL-6 binds to a complex of the IL-6 receptor α and gp130. This results in the activation of Janus kinases (JAKs) that phosphorylate signal transducer and activator of transcription 3 (STAT3). Upon phosphorylation, STAT3 dimers are formed through phosphoYXXQ motifs (Y) and translocate into the nucleus where they regulate hepcidin transcription. Adapted with permission from Heinrich et al^3 (Fig1); copyright 2003 The Biochemical Society.