Vol. 207, No. 6, June 7, 2010. Pages 1321–1332.

The authors regret that in the original version of this article the lengths of some of the scale bars in Figs. 1, 5, and 6 were incorrect. In addition, the image depicting Rag-deficient recipients of CBir1 and OTII T cells in Fig. 6 E was incorrect. All errors have been corrected in the html and pdf versions of the article, and the corrected version of Fig. 6 is shown below.