Fig. 8. Increased genomic instability in Eme1-deficient ES cells. (A) Spontaneous and MMC-induced chromosomal instability in Eme1-deficient ES cells. Metaphase spreads of untreated and MMC-treated wild-type and Eme1^–/– ES cells were analyzed for chromosomal instability. Increased spontaneous aneuploidy is observed in Eme1^–/– ES cells, with other aberrations represented by breaks, triradials and chromosomal fusions. (B) MMC treatment aggravates chromosomal aberrations in Eme1^–/– ES cells. A normal metaphase spread from untreated Eme1^–/– ES cells (1) and two metaphase spreads from MMC-treated Eme1^–/– ES cells (2 and 3) showing MMC-induced accumulation of fragments (fr) and triradials (t).