(Developmental Cell 23, 611–623; September 11, 2012) In the originally published version of this article, Figure 3A contained an incorrect immunoblot for Myc, and Figure S3D had the wrong middle lane in the IP:Myc/IB:Myc blot where no signal is detected. These errors inadvertently occurred during figure preparation, and the corrected versions are shown below. For clarity, the results of Figures S3C (right panel of S3C) to S3E are from the same experiment, and we reused controls in accordance with the journal guidelines. Additionally, we have now added lane breaks which were not required at the time of publication. The corrected version appears below; please note that these corrections do not affect the conclusions of the study. We were unable to reach the authors Sasha Haif and Lina Korsensky in the course of preparing these corrections. All other authors have approved these changes and regret the errors.