Figure 1. An unbiased genome-scale gRNA screen for novel DNA end protection factors.

(A) Flow cytometric analysis of chromatin-bound RPA before and after IR of non-cycling Lig4^−/− and Lig4^−/−:Trp53bp1^−/− abl pre-B cells. (B) Flow cytometric analysis of FLAG-Cas9 in Lig4^−/− cells with (+dox) and without (−dox) doxycycline to induce expression of FLAG-Cas9. (C) Schematic diagram of the genome-scale guide RNA screen for genes preventing DNA end resection in non-cycling Lig4^−/− abl pre-B cells. (D) Enrichment score (fold enrichment) of individual gRNAs to a subset of genes identified in the RPA high population. gRNA, guide RNA; IR, ionizing radiation.