Growth regulator. Inhibits the proliferation of a number of tumor cell lines. It regulates cytokine production, including IL-6, G-CSF and GM-CSF from endothelial cells (By similarity). Uses only type II OSM receptor (heterodimers composed of OSMR and IL6ST). Involved in the maturation of fetal hepatocytes, thereby promoting liver development and regeneration (By similarity). Propeptide processing is not important for receptor binding activity but may be important growth-inhibitory activity. Belongs to the LIF/OSM family.