Leukemia Inhibiting Factor (LIF) is a pleiotropic cytokine of the interleukin-6 family with different biological actions in various tissue systems, including modulation of cell growth and differentiation.Although named for its ability to inhibit proliferation of a myeloid leukemic cell line by inducing differentiation, it also regulates the growth and differentiation of embryonic stem cells, primordial germ cells, peripheral neurons, osteoblasts, adipocytes, and endothelial cells.