Nat. Biotechnol. 32, 364–372 (2014); published online 16 March 2014; corrected after print 8 November 2017

In the version of this article initially published, the cells labeled Me290 were Me275 cells. Both Me275 and Me290 are human metastatic HLA-A201+ melanoma cell lines, and both of them were obtained from the Ludwig Cancer Institute. Therefore, the mislabeling does not affect the conclusions of the paper. The error has been corrected in the HTML and PDF versions of the article.