May contribute to the transcriptional control of cell growth and differentiation. Antagonizes transcriptional activation and cellular transformation by the adenovirus E1A protein. The transcriptional control activity of cell growth requires interaction with IGF2R (By similarity). Homodimer. Interacts with IGF2R; the interaction is dependent on glycosylation (By similarity). Widely expressed. Found at low level from 7 dpc and increased during embryonic development. Induced during differentiation. N-glycosylated. Belongs to the CREG family.