a, Quantitation of gene targeting efficiency at the LMNA locus in asynchronously dividing U2OS cells transfected with increasing amount of donor template and with (black) or without (grey) gRNAs. Gene targeting events were detected by flow cytometry (mean ± s.d., N≥3). b, Quantitation of gene targeting efficiency at the LMNA locus in asynchronously dividing cells transfected with the indicated siRNA. Gene targeting events were detected by flow cytometry (mean ± s.d., N=3). c, Gene targeting efficiency at the PML locus measured by flow cytometry in G1-arrested 53BP1Δ U2OS cells expressing the CtIP-T847E mutant and co-transfected with the indicated siRNA or a PALB2-KR expression construct (mean ± s.d., N=3). d, Representative FACS profiles showing the gating for 1N DNA content cells and the detection of mClover-positive cells in the LMNA gene targeting assay in asynchronous (ASN) or G1-arrested 53BP1Δ U2OS cells expressing the CtIP-T847E mutant and co-transfected with the indicated siRNA or a PALB2-KR expression construct. e, Gene targeting efficiency at the LMNA locus measured by flow cytometry in G1-arrested parental (WT) and 53BP1Δ U2OS cells transfected with KEAP1 siRNA and expressing the CtIP-T847E mutant (mean ± s.d., N=3). f, Gene targeting efficiency at the LMNA locus measured by flow cytometry in G1-arrested parental (WT) and 53BP1Δ U2OS cells transfected with the indicated siRNA and expressing either wild-type (WT) or the CtIP-T847E mutant (mean ± s.d., N=3).