Modulation of migration of CD34⁺ cells and megakaryocytic progenitor cells by SDF-1α. CD34⁺ cells were isolated from bone marrow by immunoadsorption using the CellPro Ceprate LC system. Migration of isolated CD34⁺ cells and CFU-Meg was measured as described in Materials and Methods. The migration of CD34⁺ cells or CFU-Meg was shown as the percentage of cell input. Results represent the mean ± SD of four separate experiments. * and ** show statistical significance compared with control and are assessed as P < .05 andP < .01, respectively.