Depletion of SUMO conjugates in the human colon carcinoma cell line HCT116 and the fibrosarcoma cell line HT-1080 by knockdown of either the SAE or the SUMO-conjugating enzyme (UBC9) by infection with lentivirus expressing short hairpin RNAs (shRNAs) against these enzymes had an even bigger effect on the formation of chromatin bridges (Supplementary Fig. 1). The gene discussed is UBE2I; the disease is infection.