NHEJ efficiency and fidelity in Ba/F3 cell lines. WCE from a DNA Ligase IV-deficient cell line (N114) and parental lymphoid cell line (Nalm6) and Ba/F3-EPOR cells were incubated with the linearized plasmids pEGFPN2 (A) or pBluescript (B) for in vitro analysis of DNA end-ligation activities. The reaction products were run on agarose gel and stained with SYBR-Green. Multimerized DNA molecules (nX) were formed. Linearized plasmid can also be found in supercoiled state (sc). (C) Scheme of PCR products and the expected sizes of these fragments after restriction enzyme cleavage for the analysis of error-prone NHEJ. (D) Ba/F3-HR2 cells were infected or not with I-SceI virus, incubated for 96 hours for DSB repair to take place, EGFP⁺ cells were excluded by FACSsort, genomic DNA isolated, and PCR analysis performed. A representative gel shows the PCR fragments with and without I-SceI and XhoI digestion for the 3 Ba/F3 cell lines.