In addition, in 1999, we demonstrated that interleukin-17 (IL-17), which was first cloned in 1995, potently induces murine osteoclastogenesis via the expression of RANKL on murine osteoblasts, and that IL-17 is present in synovial fluid and tissues from patients with RA [4]. This evidence concerns the gene IL17A and rheumatoid arthritis.