Leukemia Inhibitory Factor (LIF) is a member of the interleukin-6 (IL-6) family that is made by a variety of adult and embryonic tissues. LIF signals through the glycoprotein 130 (gp130)/LIF receptor (LIFR) heterodimer to activate STAT3 and MAPK signaling. LIF functions during hematopoietic differentiation, neuronal cell differentiation, kidney development, and inflammatory processes. The application of mouse LIF to long-term culture systems promotes mouse embryonic stem cell (ESC) self-renewal and pluripotency, similar to the functional activity of FGF-2 in human ESC cell culture systems.