Kishimoto and coworkers found evidence that bone marrow cells isolated from rats with collagen-induced arthritis were less affected by disease mechanisms than synovial tissue as they found highly up-regulated pro-inflammatory cytokine mRNA as well as osteoclast markers cathepsin K, TRAP and Rank receptor which was much less apparent in bone marrow cells [31]. The gene discussed is ACP5; the disease is arthritic joint disease.