BGLAP and rheumatoid arthritis: The finding that more calcium minerals are formed and deposited in chondrogenesis condition, together with the previous finding that the protein level of BGLAP/osteocalcin is significantly higher in the OA synovial fluid than that in RA synovial fluid [46], suggests a potential role of FLSs differentiation-inducing factors in the OA FLSs-medicated pathological calcification process.