MMP9 and osteoarthritis: siRNA targeting of NF-κB p65 subunit has shown promising effects by suppressing the IL-1β/TNF-α induced gene expression of cyclooxygenase-2 (COX-2), nitric oxide synthase-2 (NOS-2), and matrix metalloproteinase-9 (MMP-9), which is paralleled with the initiation and progression of cartilage lesions in osteoarthritis [47].