DKK1 (Dickkopf-1) is a secreted protein that acts as an inhibitor of the Wnt signaling pathway, which plays a crucial role in regulating cell growth, development, and bone formation. By blocking Wnt interaction with its receptors, DKK1 affects processes such as cell differentiation, proliferation, and bone density. Its activity is associated with conditions like osteoporosis and various cancers, making it a potential target for therapeutic approaches.