Cartducin, a paralog of Acrp30⁄adiponectin, is a secretory protein pro-duced by both chondrogenic precursors and proliferating chondrocytes, and belongs to a novel C1q family of proteins. We have recently shown that cartducin promotes the growth of both mesenchymal chondroprogeni-tor cells and chondrosarcoma-derived chondrocytic cells in vitro.