The following antibodies were used for immunofluorescence (IF) and immunoblotting (IB) at indicated dilutions: sheep anti-pan-RNase H2 (raised against human recombinant RNase H213 (link), IB 1:1,000, IP 5 µl / 1 ml lysate); rabbit anti-RNASEH2C (Proteintech 16518-1-AP; IB 1:1,000); rabbit anti-RNASEH2A (Origene TA306706, IB 1:1,000); mouse anti-RNASEH2A (Abcam ab92876; IF 1:500); mouse anti-RNASEH2A G-10 (Santa Cruz Biotechnologies sc-515475; WB 1:1000); mouse anti-γH2AX JBW301 (Millipore 05-636, IF 1:800 – 1:2,000); rabbit anti-RAD51 H-92 (Santa Cruz Biotechnologies sc-8349, IF 1:150); rabbit anti-BRCA146 (link) (IB 1:1,000); mouse anti-Cas9 (Diagenode C15200203, IB 1:1,000); rabbit anti-PARP1 H-250 (Santa Cruz Biotechnologies sc-7150, IB 1:1,000); mouse anti-PAR 10H (Enzo ALX-804-220-R100, IB 1:1,000); rabbit anti-Topoisomerase I (Abcam ab109374; IB 1:5,000); rabbit anti-DYKDDDDK (Cell Signaling Technologies 2368, IB 1:1,000); rabbit anti-actin (Sigma A2066, IB 1:5,000); mouse anti-α–tubulin DM1A (Millipore CP06, IB 1:5,000); mouse anti-α–tubulin B512 (Sigma T6074, IB 1:5,000); rabbit anti-GAPDH (Sigma G9545, IB 1:20,000); mouse anti-vinculin (Sigma V9264, IB 1:1,000); rabbit anti-DNA polymerase beta (Abcam ab26343, IB 1:1,000); rabbit anti-cleaved caspase-3 (Cell Signaling Technologies 9661S, IF 1:800).