POLθ promoted leukemogenesis of HR/D-NHEJ–proficient and HR/D-NHEJ–deficient cells. (A) Clonogenic activity of Lin^-cKit⁺Polq^−/− and Polq^+/+ GFP⁺ bone marrow cells expressing GFP (normal) and the indicated oncogenes. Results represent mean ± SD number of colonies; ∗P < .05 when compared with Polq^+/+ counterparts using t test. (B) Proliferation of Lin^-cKit+ Polq^−/− and Polq^+/+ bone marrow cells expressing GFP (normal) and the indicated oncogenes. Results represent mean ± SD number of cells; ∗P < .05 using t test. (C) DSBs were assessed by neutral comet assay in Polq^+/+ (blue bars) and Polq^−/− (orange bars) Lin^- mBMCs expressing GFP (normal) and the indicated oncogenes. Results represent mean olive tail moment ± SD; ∗P < .05 when compared with Polq^+/+ counterparts using t test. (D) Mean ± SD number of colonies from Lin^- bone marrow cells harvested from Flt3^ITD;Polq^−/− (n=2) and Flt3^ITD;Polq^+/+ (n=4) mice; ∗P < .05 when compared with Polq^+/+ counterparts using t test. (E) Engraftment of BCR-ABL1–positive Polq^+/+ and Polq^−/− cells in sublethally irradiated syngeneic mice. Results represent the mean percentage ± SD of GFP⁺ cells detected 4 weeks after transplantation in 10 mice per group. ∗P < .05 using t test. SD, standard deviation.