TNF and rheumatoid arthritis: To further study the effect of BMP3 on the proinflammatory cytokines and chemokines of RA FLS, we used the overexpression plasmids BMP3-pcDNA3.1 for humans and BMP3-PEX for rats to induce overexpression of BMP3 in TNF-α–treated RA and AIA FLS, respectively.