Correction to: Cell Death and Disease (2011) 2, e246; doi:10.1038/cddis.2011.128; published online 22 December 2011

Since the publication of this article, the authors have noticed that labeling at the top of figure 6a and b was incorrect.

This error has now been rectified. The article with the corrected figure appears online, together with this corrigendum.

The authors would like to apologize for this error.