(Related to Fig. 2 ): Sister chromatids are separated during DNA combing but not spreading in U2OS cells. (A) DNA combing assay performed by the Vindigni laboratory as depicted in Fig. 1 A. Green-only versus red–green or red–green–red tracts are scored and represented as percentage of total pulse-labeled tracts. At least 100 tracts were scored for each sample. Numbers indicate the mean tracts %. Statistics: mean ± SEM. Number of biological repeats N = 3. (B) DNA spreading assay performed by the Vindigni laboratory as depicted in Fig. 1 A. Green-only versus red–green or red–green–red tracts are scored and represented as percentage of total pulse-labeled tracts. At least 100 tracts were scored for each sample. Numbers indicate the mean tracts %. Statistics: mean ± SEM. Number of biological repeats N = 3.