Glycoprotein 13 (also known as gp13, IL6ST, IL6-beta or CD13) is a transmembrane protein which is the founding member of the class of all cytokine receptors. CD13/gp13 is a signal transducer shared by many cytokines, including interleukin 6 (IL6), ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), and Oncostatin M (OSM). CD13/gp13 functions as a part of the cytokine receptor complex. The activation of this protein is dependent upon the binding of cytokines to their receptors. CD13/gp13 plays a critical role in regulating myocyte apoptosis. Alternatively spliced transcript variants encoding distinct isoforms have been described. A related pseudogene has been identified on chromosome 17. The receptor systems for IL6, LIF, OSM, CNTF, IL11, CTF1 and BSF3 can utilize gp13 for initiating signal transmission. CD13/gp13 binds to IL6/IL6R (alpha chain) complex, resulting in the formation of high-affinity IL6 binding sites, and transduces the signal. CD13/gp13 may have a role in embryonic development. The type I OSM receptor is capable of transducing OSM-specific signaling events.