CCL2 and rheumatoid arthritis: Because MCP-1 is a potent chemotactic factor that triggers the infiltration of monocytes/macrophages into inflammatory sites [15], expression of MCP-1 is an indicator for many inflammation-associated pathological states, such as dermatitis [6], rheumatoid arthritis, atherosclerosis [40], diabetic nephropathy [39], lung inflammation [40] and cancer [41].