For radiolabeling experiments, HeLa cells were lysed in TENTG-150 buffer, and DNA was extracted with phenol/chloroform/isoamyl (pH 8) (12/12/1). DNA was subsequently dephosphorylated using Shrimp Alkaline Phosphatase (rSAP) New England Biolabs (NEB) before labeling with γ32P ATP for 30 min at 37°C using the T4 polynucleotide kinase (NEB). Subsequent RNaseH treatment was performed with 10, 20, or 40 U following the manufacturer’s protocol. Unbound radiolabeled nucleotides were removed using Illustra Microspin G-50 Columns before resolution on 5% acrylamide, 0.5% tris borate ethylamide gel, and autoradiography. Images were acquired using Thyphoon FLA 7000.