Moreover, gene expression analysis of cultured OCPs showed that osteoclast-differentiation genes (c-Fos, CD115/c-Fms, and Rank) and chemokine CCL2 are induced in the CCR2lo subset of both adjuvant-treated and arthritic groups, whereas arthritis-specific enhancement was observed in CCR2hi OCPs. Here, CCL2 is linked to Arthritis.