Pol δ function promotes chromosomal translocations. (A) Translocation frequency in the CRITR assay (30) using 293T cells after depletion of POLD1 or POLD2. siCTRL indicates nontargeting control. Cells were transfected with the indicated siRNA at 0 h and at 72 h they were transfected with the same siRNA and Cas9/gRNA. Cells were collected after 48 h for flow cytometry and immunoblotting. (B) Translocation frequency in the CRITR assay using 293T cells stably transduced with empty vector (EV) or Myc-tagged, siRNA-resistant POLD1 WT, D316G, or S605del. Cells were transfected with siCTRL or siPOLD1 #2 (D1) and 72 h later transfected with the same siRNA and Cas9/gRNA. Cells were collected after 48 h for flow cytometry and immunoblotting. (C) Cell cycle dynamics for 293T cells transfected with siCTRL or siPOLD1 and transduced with siRNA-resistant POLD1 constructs, as indicated. Data are presented as mean ± SE of n = 3 independent experiments. P values calculated using a one-way ANOVA with Tukey’s correction. No statistically significant differences were observed in C. **P < 0.01, ****P < 0.0001.