Plays a role in the regulation of the early stage of white and brown preadipocyte cell differentiation. Promotes adipogenic commitment of preadipocytes by increasing gene expression of the transcription factor PPARG in a BMP4-dependent signaling pathway. Homodimer. Secreted by adipose precursor cells (By similarity). Not detected in the nucleus (PubMed:28052263). Expressed early in fetal white adipose tissues from 17 to 21 weeks of gestation (at protein level). N-glycosylated. N-linked glycosylation is critical for secretion but not for preadipocyte cell differentiation activity. Truncated N-terminus. Truncated N-terminus.