Nature Immunology 3, 687–694 (2002).

In the July issue of Nature Immunology the sentence on page 693, paragraph 1, line 8, should have read: ”An increased production of human MMP-2 and MMP-9 by G-CSF–mobilized CD34+ cells and by steady-state CD34+ cells in the circulation, but not steady-state BM CD34+ cells, suggests that these enzymes are involved in the transendothelial migration of immature cells into the periphery52,53.”