General gp130 activation by the interleukin-6 (IL-6)/soluble IL-6 receptor (sIL-6R) complex. Because all depicted receptor complexes of IL-6 family cytokines contain at least one molecule of gp130, the IL-6/sIL-6R complex can substitute for the activity of all depicted IL-6 family cytokines leading to signal transducer and activator of transcription 3 (STAT3) activation. CLC, Cardiotrophin-like cytokine; CNTF, ciliary neurotrophic factor; LIF, leukemia inhibitory factor; OSM, oncostatin M.