CCL4 and systemic sclerosis: Profibrotic features associated with monocytes from both SSc-ILD and healthy AA subjects include the enhanced expression of chemokine receptors CXCR4 and CCR5, enhanced migration toward their respective chemokine ligands (SDF-1 for CXCR4, MIP-1α and MIP-1β for CCR5), and enhanced differentiation into fibrocytes [10, 12, 19].