This paper has been retracted due to manipulation in Figure S2c.
On August 27, 2013, an Expression of Concern was posted on this article alerting readers to an investigation by the University of Utah, now completed. Authors J. Cappello, H. Ghandehari, J. A. Gustafson, J. J. Magda, and L F. Pease III have been adjudicated not guilty of research misconduct by the University of Utah. The expression of concern has been removed upon retraction of this article.
The original article was published on June 22, 2011, and retracted on November 3, 2014.