Mdk encodes a secreted growth factor that belongs to the pleiotrophin/midkine heparin-binding protein family and functions in a variety of biological processes. The encoded cytokine promotes the growth, differentiation, survival and migration of several target cells including leucocytes involved in inflammation. This protein plays a role in the formation of scar tissue and intraperitoneal adhesions, and promotes neurite outgrowth and neuron survival. The protein encoded by Mdk is associated with obesity and inhibition of insulin signaling in fat cells. A pseudogene of Mdk is present on chromosome 11. Alternative splicing results in multiple transcript variants.