Early pro-B and lineage-negative BM cells from FLT3/ITD mice show decreased expression of Ku86 and increased expression of PARP1. (A) RNA was extracted from sorted early pro-B cells, reverse transcribed, and subjected to quantitative RT-PCR assays. Data are representative of 5 independent experiments. (B) Western blotting analysis using nuclear extracts from sorted early pro-B cells (i-ii) demonstrates decreased expression of Ku86 and increased expression of PARP1 in samples from FLT3/ITD mice. Lamin B was used as a loading control. (C) Transduction of Ku86 into FLT3/ITD Lin⁻ BM partially overcomes the block of B-lymphocyte development in recipients. Representative flow cytometry analyses of recipient PB and BM are shown. GFP⁺B220⁺CD19⁻ cells from recipients transplanted with Ku86-transduced FLT3/ITD Lin⁻ cells demonstrate increased repair efficiency (D) and the use of less and shorter microhomologous sequences (E) for the repair of DNA. (F) Quantitative RT-PCR (i) and Western blotting assay (ii) of lineage-depleted BM cells from FLT3/ITD mice have significantly decreased Ku86 and increased PARP1 expression compared with control mice. Data are mean ± SEM (error bars). Data are representative of 3 independent experiments. Values below the gel image indicate relative fold changes of protein levels normalized to lamin-B.