Fig. 2: Proper chromosome alignment requires CHK2 Y156 phosphorylation.

A Western blots showing CHK2 expression in parental HeLa, HeLa with CHK2 knockout (KO), and KO cells reexpressing WT (clones #58, #103) or Y156F CHK2 (clones #A2, Y2). B Proportions of cells that were not properly arrested by overnight nocodazole treatment (25 ng/mL). Representative images for improper arrest are shown in Fig. S3B. Shown is mean ± SD from four independent experiments with each 50–60 cells analyzed. C–E Chromosome alignment after release from nocodazole-mediated mitotic arrest as assessed using confocal microscopy. Representative images captured after 1 h following the release are shown in (C). Increased chromosome misalignment was observed in KO cells at 30 min (D) and 1 h (E) after release, which can be rescued by the reexpression of WT but not Y156F CHK2. Representative images for improper chromosome alignment are shown in Fig. S3C. Mean ± SD from four independent experiments is shown with each 50–60 cells examined. Scale bar, 10 μM.