The increased CXCR4 levels are consistent with the findings from other groups where CXCR4 expression was measured in lung tissues and peripheral blood monocytes.18, 19 A recent study reported that CXCR4 is the most commonly expressed marker in the differentiation of circulating progenitor cells in patients with SSc interstitial lung disease, followed by CD34 and CD45.20 We show that silencing IGFBP‐4 expression in human lung fibroblasts increased levels of CXCR4. The gene discussed is PTPRC; the disease is systemic sclerosis.