The authors would like to thank F. d'Adda di Fagagna and S.P. Jackson for discussions of unpublished results. Due to an editorial oversight, this statement was inadvertently omitted from the Acknowledgments. The entire section appears correctly below:
We thank P. Lansdorp and S.S. Poon for providing the TFL Telo image analysis program; C. Heyting for providing SCP3 antibodies; T. de Lange for providing the retroviral constructs and TRF1 antibodies; R. Hodes for helpful discussions and critical comments on the manuscript; and F. d'Adda di Fagagna and S.P. Jackson for discussions of unpublished results.