The pleiotropic actions of leukemia inhibitory factor.

Leukemia inhibitory factor (LIF) is a glycoprotein regulator that induces the differentiation and suppresses the clonogenicity of M1 myeloid leukemic cells. M1 cells require only a brief exposure to LIF to become irreversibly committed to differentiation. In combination with granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor, LIF is also able to suppress HL-60 and U937 cell proliferation. Normal monocytes and macrophages have LIF receptors, but the function of LIF on such cells is unclear. Recently it was discovered that LIF also acts on embryonic stem (ES) cells, where its continuous presence is required to prevent ES cell differentiation.