Nat. Med.; 10.1038/nm.3655; corrected online 22 September 2014

In the version of this article initially published online, the third sentence of the Abstract read “Gene expression analysis identified higher expression of JAK-STAT signaling targets in 3-week-old relative to 18-month-old mice,” when it should have read “Gene expression analysis identified higher expression of JAK-STAT signaling targets in 18-month-old relative to 3-week-old mice.” The error has been corrected for the print, PDF and HTML versions of this article.