The Rockefeller University Press $30.00 J. Cell Biol. Vol. 206 No. 4 493–507 www.jcb.org/cgi/doi/10.1083/jcb.201404111 JCB 493 Correspondence to James A. Borowiec: James.Borowiec@nyumc.org Abbreviations used in this paper: CldU, 5-chloro-2-deoxyuridine; CPT, camptothecin; DSB, DNA double-strand break; HR, homologous recombination; HU, hydroxyurea; IdU, 5-iodo-2-deoxyuridine; PARP, poly-ADP ri...