Although human BM CD34+ cells are considered hematopoietic cells, the cell surface markers used to identify these human hematopoietic cells are different from cell surface markers used to identify murine hematopoietic cells, and murine CD34+ cells behave differently from human CD34+ cells.9 Human CD34+ cells have been used successfully for BM transplantation in patients with hematologic disorders. The gene discussed is CD34; the disease is hematologic disorder.