We have identified two distinct populations of CXCR4+ cell, one of epithelial origin (CXCR4+/e-cadherin+) and one of myeloid origin (CXCR4+/CD45+), that were increased in lung tissue of patients with IPF compared to non-diseased control (NDC) donors. The gene discussed is PTPRC; the disease is idiopathic pulmonary fibrosis.