Vol. 212, No. 12, November 16, 2015. Pages 2057–2075.

The Journal of Experimental Medicine regrets that due to a production error, the original version of this paper included incorrect labels to the right of the blots in Fig. 8 B. The legend remains correct, and the corrected figure appears below. The online HTML and PDF versions of this article have been corrected. The error only remains in the print version.