NFKB1 and rheumatoid arthritis: MMP-2 and MMP-9, also called collagenases, degrade type IV collagen, gelatin and elastin, and are induced in RA-FLS by pro-inflammatory cytokines, through the activation of transcription factors such as nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) [15].