LIF is a pleiotropic cytokine with roles in several different systems. It is involved in the induction of hematopoietic differentiation in normal and myeloid leukemia cells, induction of neuronal cell differentiation, regulator of mesenchymal to epithelial conversion during kidney development, and may also have a role in immune tolerance at the maternal-fetal interface. LIF was initially recognized by its ability to induce terminal differentiation of myeloid leukemic cells. It is a member of the IL-6 cytokine superfamily and can be highly glycosylated. LIF signaling is transduced through the LIF-R/gp130 receptor complex, leading to the phosphorylation and activation of the JAK/STAT pathway. Recent evidence shows that LIF inhibits cardiomyogenesis in embryonic stem cells via STAT3 activation.