Leukemia inhibitory factor (LIF) is an interleukin 6 family cytokine that affects cell growth by inhibiting differentiation. When LIF levels decrease, cells differentiate. Activated T cells, monocytes, astrocytes, osteoblasts, keratinocytes, mast cells, and fibroblasts can express LIF.LIF is named for its ability to induce terminal differentiation of myeloid leukemia cells and to prevent the continued growth of leukemia cells.Other properties of LIF include growth promotion, promotion of the differentiation of different types of target cells, effects on bone metabolism, malignant stigmata, neuronal development, embryonic development, and inflammation.LIF is involved in the process of endometrial metaplasia and embryo implantation into the endometrium during pregnancy. Women with decreased levels of LIF and other cytokines are more likely to become pregnant, but have an increased risk of unexplained recurrent miscarriages. Research suggests that recombinant human LIF may help improve the rate of implantation in women with unexplained infertility. In addition, LIF is commonly used to reduce spontaneous differentiation by adding it to stem cell culture media.