a. Quantification of resected ssDNA in U2OS cells expressing pBabe-empty vector or pBabe-TRIP13 measured by SMART assay. Lines indicate mean and SEM, n = approximately 100 fibers per genotype, p<0.0001 (Mann-Whitney test, two-tailed). b. Representative images for (a), with BrdU in exposed ssDNA tracts labeled red. (Scale bar: 1 μm) c. Proportion of U2OS cells expressing pBabe-empty vector or pBabe-TRIP13 with greater than 10 p-RPA32(S33) foci 6 hours following IR treatment. n = 3 biologically independent experiments, p = 0.002 (Student’s t-test, two-tailed). d. Western blot showing TRIP13 knockout in HeLa cells. e. Proportion of HeLa cells with greater than 10 p-RPA32(S33) foci 6 hours following IR treatment. f. Western blot showing RPA32 phosphorylation (S33) and H2AX phosphorylation, with or without irradiation in wild-type or TRIP13−/− U2OS cells, expressing Empty vector or TRIP13-E253Q. g. Proportion of U2OS cells expressing Empty vector or TRIP13 with greater than 10 RAD51 foci 6 hours following IR treatment. n = 3 biologically independent experiments, p = 0.01 (Student’s t-test, two-tailed). h. Proportion of HeLa cells with more than 10 RAD51 foci 6 hours following IR treatment. n=2 biologically independent experiments. i. Western blot showing TRIP13 knockdown for DR-GFP experiment in 4g. j. Percentage of GFP-positive cells following infection of U2OS DR-GFP cells expressing FLAG empty vector or FLAG-TRIP13 with I-SceI adenovirus. n = 3 biologically independent experiments, p = 0.05 (Student’s t-test, two-tailed). All error bars indicate SEM. All immunoblots are representative of at least 2 independent experiments.