Furthermore, IHC analysis of fractured tissue at 10 dpf revealed abundant expression of SPP1 and CXCL12 in the fractured calluses of control mice but almost nondetectable expression of SPP1 and CXCL12 in the fractured calluses of RA mice (Fig. 3b), confirming the downregulation of SPP1 and CXCL12 mediated by inflammation in the context of fracture repair under RA conditions. The gene discussed is CXCL12; the disease is rheumatoid arthritis.