FAM20B and chondrosarcoma: The inactivation of Fam20b in the murine skeleton by Col1-cre caused a malformed annulus fibrosus in the spine and intervertebral disc by suppressing TGF-β signaling [21], and deleting Fam20b in the popliteal cartilage of the mouse knee joint resulted in a chondrosarcoma by enhancing multiple signaling pathways [22].