Figure 6. The Rad9-S272C mutant cells accumulate chromosome breakages and show chromosome instability phenotypes. (A) Chromosome breakages in Rad9 and Rad9-S272C cells. An example of metaphase spread of a Rad9-S272C cell (top, left). The Rad9-S272C cells induce a high frequency of chromosome breakages without damage (top, right), after IR treatment (3 Gy) (bottom, right), after CPT treatment (500nM, 6 h) (bottom, left). (B) The Rad9-S272C mutant cells induce a high frequency of GCRs, chromosome rearrangements. Twenty cells for each cell line were karyotyped and chromosome abnormalities were detected.