DLK-1, also known as preadipocyte factor 1 （Pref-1）, is a transmembrane-secreted protein containing an epidermal growth factor （EGF）-like repeat sequence. It is expressed on the cell surface in various cancers, including hepatocellular carcinoma, and may serve as a potential target for monoclonal antibody therapy. DLK-1 regulates the growth of pioneer axons by modulating Wnt signaling. While primarily expressed as a transmembrane protein, a soluble form generated by ADAM17-mediated cleavage is active in inhibiting adipogenesis, the process by which pre-adipocytes differentiate into adipocytes.