MMP1 and rheumatoid arthritis: Kaempferol reduced the production of matrix metalloproteinases-1 (MMP-1), matrix metalloproteinases-3(MMP-3), COX-2, and prostaglandin E2 (PGE2) in response to interleukin-1β (IL-1β) as well as the proliferation of both unstimulated and IL-1β-stimulated rheumatoid arthritis synovial fibroblasts.