Since fibrocytes are derived from monocytes, SSc monocytes overexpress CXCR4 and CXCR4 mediates the migration of monocytes and fibrocytes into injured lung tissue [8], we used micro-Boyden chambers (in which cells placed in the upper chamber migrate through a membrane toward the chemoattractant placed in the lower chamber) to compare the migration of SSc and normal monocytes in response to CXCL12. This evidence concerns the gene CXCR4 and systemic sclerosis.