Fig. 2. Persistence of sister chromatid cohesion on arms depends on a cohesin complex protected by Sgo1. (A) Schematic overview of synchronization and RNAi treatment. HeLa cells were transfected with a mock or siRNA to Sgo1 during synchronization by the double-thymidine-block protocol and 25 µM MG132 was added at G2/M transition. Mitotic cells were collected at the indicated times (hours) after MG132 treatment and analyzed by Giemsa staining of chromosome spreads. (B) Reduction of Sgo1 in the collected mitotic cells was assessed by immunoblot analysis. (C) Representative chromosomes with paired (left) or unpaired (right) sister chromatids are shown. Insets show magnified images of the single chromosome in the boxed regions. (D) Quantification results from 200 cells for each time-point are summarized in the histogram. The dark-grey and white population represents cells containing unpaired and paired chromatids, respectively. An unclassified population is shown in light grey.