Fig. 3.

Signal transduction pathways of interleukin-6 (IL-6): (A) classical signal transduction; (B) trans signal transduction; and (C) trans-presentation. (D) The next step is to activate the Janus kinase/signal transducer and activator of transcription (JAK-STAT) pathway (STAT1, STAT3 and, to a lesser extent, STAT5); in addition, the RAS-RAF, SRC-YAP-NOTCH and AKT-PI3K pathways are also activated. These promote complex biological functions such as proliferation, differentiation, oxidative stress and immune regulation, etc. IL-6R, interleukin-6 receptor; gp130, glycoprotein 130; sIL-6R, soluble interleukin-6 receptor; sgp130, soluble glycoprotein 130;