By IF these cells were c-Kitlow/CD45-/CD31+, suggesting an endothelial lineage, and were predominantly located in the alveolar wall; and, (4) by FACS, an infrequent c-Kitlow/CD45-/CD34- population (0.09 ± 0.14% (NS), 0.08 ± 0.09% (S) and 0.08 ± 0.11% (COPD)) compatible with a putative lung stem cell population. The gene discussed is CD34; the disease is chronic obstructive pulmonary disease.