Cytokine that may play an important role during carcinogenesis and metanephric kidney organogenesis, as a BMP antagonist required for early limb outgrowth and patterning in maintaining the FGF4-SHH feedback loop. Down-regulates the BMP4 signaling in a dose-dependent manner (By similarity). Antagonist of BMP2; inhibits BMP2-mediated differentiation of osteoblasts (in vitro) (By similarity). Acts as inhibitor of monocyte chemotaxis. Can inhibit the growth or viability of normal cells but not transformed cells when is overexpressed (By similarity). Homodimer; can also form homooligomers. Interacts with BMP2; can form higher oligomers with BMP2 (By similarity). Interacts with SLIT1 and SLIT2 in a glycosylation-dependent manner (By similarity). Belongs to the DAN family.