Human LIF (leukemia inhibitory factor) protein suppresses the differentiation of embryonic stem cells (ESCs) and is widely used in ESC and iPSC culture. Human LIF can be used in the maintenance of both murine and human ESCs in feeder or feeder-free chemically defined culture systems. LIF is a pleiotrophic factor that belongs to the IL-6 superfamily of cytokines. Acting through a heterodimeric receptor of gp130 and gp190, LIF can activate a number of cellular pathways including the JAK/STAT, PI3K and MAPK pathways. Qkine human LIF protein is high purity and animal and carrier-protein free for reproducible results.