Nature Immunology 7, 755–762 (2006); published online 28 May 2006; corrected after print 20 June 2006

In the version of this article initially published, the key and figure labels for Figure 8c are incorrect. The gray bars are C1R–A2–MICA–M27, the filled bars are C1R–A2–M27, and the cells are CD8+ (not CD4+). The error has been corrected in the HTML and PDF versions of the article.