TNF and rheumatoid arthritis: Furthermore, fibroblast-like synoviocytes from patients with RA have been demonstrated to express BMP receptors [17] and to upregulate the expression of BMP2 and mainly BMP6 after stimulation with pro-inflammatory cytokines such as TNF-α, interleukin-1beta (IL-1β), and IL-17 [14, 18, 19].