In the article “Requirement for DNA Ligase IV during Embryonic Neuronal Development,” by Susanne A. Gatz, Limei Ju, Ralph Gruber, Eva Hoffmann, Antony M. Carr, Zhao-Qi Wang, Cong Liu, and Penny A. Jeggo, which originally appeared on pages 10088–10100 of the July 6, 2011 issue, the author contributions were indicated incorrectly. Dr. Susanne A. Gatz is the single first author of this manuscript. Dr. Cong Liu and Dr. Penny A. Jeggo contributed equally to this work. This work was additionally supported by the Chinese NSF funding (30970950).