Chicken Midkine (MK) is a heparin-binding growth factor and cytokine that plays important roles in cell growth, development, and tissue repair in chickens (Gallus gallus). Midkine is highly expressed during embryonic development and can also be induced in adult tissues in response to injury, inflammation, or physiological stress. Chicken midkine interacts with several cell surface receptors, including receptor-type protein tyrosine phosphatase ζ (PTPRZ1), low-density lipoprotein receptor–related proteins (LRPs), and integrins, activating intracellular signaling pathways such as MAPK, PI3K–AKT, and NF-κB that regulate cell proliferation, migration, and survival. Through these mechanisms, midkine contributes to processes including tissue regeneration, angiogenesis, immune cell recruitment, and regulation of inflammatory responses. In chickens, midkine is involved in developmental processes such as neural development and tissue differentiation and may also contribute to immune regulation during infection or tissue injury. In cell culture, recombinant chicken midkine is commonly used to stimulate cell proliferation and migration, study growth factor–mediated signaling pathways, and investigate mechanisms of tissue development, regeneration, and inflammatory signaling in vitro.