Chromatin immunoprecipitations were performed with cross-linked chromatin from 4 x 10 6 HeLa cells and either 10 μl of RNF20 (D6E10) XP ® Rabbit mAb or 2 μl of Normal Rabbit IgG #2729 using SimpleChIP ® Enzymatic Chromatin IP Kit (Magnetic Beads) #9003. The enriched DNA was quantified by real-time PCR using SimpleChIP ® Human γ-Actin Promoter Primers #5037, SimpleChIP ® Human GAPDH Promoter Primers #4471, and SimpleChIP ® Human α Satellite Repeat Primers #4486. The amount of immunoprecipitated DNA in each sample is represented as signal relative to the total amount of input chromatin, which is equivalent to one.