CCL2 and rheumatoid arthritis: During RA, FLS participate in disease progression (Bottini and Firestein, 2012) by releasing cytokines and growth factors like MCP-1 (Kumkumian et al., 1989), VEGF (Palmer et al., 2008), IL-6 (Guerne et al., 1989) and GM-CSF (Parsonage et al., 2008), supporting leucocyte recruitment, delaying neutrophil apoptosis and propagating pannus hyperplasia.