STAT3 and fatty liver disease: Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that can be activated by many molecules including interleukin (IL)-6 and its related cytokines, IL-22 and interferon-α/β/γ, and it plays an important role in liver injury, hepatic steatosis, inflammation and regeneration (Wang et al., 2011).