CCL2 and rheumatoid arthritis: The most prevalent was osteoarthritis (n = 1568), followed by metabolism (n = 1013), macrophage (n = 858), inflammation (n = 833), protein expression (n = 640), interleukin-6 (n = 632), interleukin-1β (n = 612), tumor necrosis factor (n = 583), human cell (n = 558), animal model (n = 535), synovium (n = 523), animal tissue (n = 472), animal experiment (n = 472), gene expression (n = 465), rheumatoid arthritis (n = 464), genetics (n = 428), monocyte chemotactic protein-1 (n = 427), chondrocyte (n = 411), and signal transduction (n = 411).