About the Authors
Howard Hughes Medical Institute, Children's Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
The authors have declared that no conflicts of interest exist.
HX, JJ, LJD, NCA, and DEC conceived and designed the experiments. HX and JJ performed the experiments. HX and JJ analyzed the data. HX, NCA, and DEC wrote the paper.