XIAP and chondrosarcoma: Although XIAP was recognized as an adaptor for BMPR signaling through the Smad-independent pathway,18, 19, 20 LDN-193189, a BMP signaling inhibitor, was used to block the BMP/Smad pathway to determine whether XIAP was loaded in the downstream of Smad-dependent pathway or -independent pathway in chondrosarcoma cells.