Nat. Med. 15, 42–49 (2009); published online 21 November 2008; corrected after print 6 April 2009

In the version of this article initially published, the labeling in (Figure 4) was incorrect. In panel (b), the cells in the left two FACS plots are shown based on their size (FSC, y axis) and CD11b expression (x axis), and the cells in the right two FACS plots are shown based on their F4/80 expression (y axis) and GR1 expression (x axis). In panel (c), the curves should start at 1 h. In panel (d), the text labeling the y axis should read “in vitro”, not “in vivo.” The errors have been corrected in the HTML and PDF versions of this article.