Geminin overexpression promotes survival of DNA-damaged cells, leading to aneuploidy. (A) Comet assay performed using Gem9 cells grown in the absence (left) or presence (right) of 2 μg/mL doxycycline (Dox) for 72 hours. (B) Quantification of the percentages of cells with DNA tails in the comet assay shown in (A) in uninduced Gem9, induced Gem9 or induced Gem9 cells transfected with CKIε or Cdc7 cDNA. Values presented are means ± SD. **P ≤ 0.01. (C) Expression of cyclin A, cyclin B1, cell division kinase 1 (Cdk1), checkpoint protein 1 (Chk1), phosphorylated Chk1 (p-Chk1) and γ-H2AX in Gem9 cells grown in the presence or absence of 2 μg/mL doxycycline for 72 hours. (D) Percentage of G1, S, G2/M, tetraploid (> 4 N) and apoptotic (sub-G1) cells detected using fluorescence-activated cell sorting (FACS) analysis in HME or uninduced or induced Gem9 cells. (E) Metaphase spread of uninduced (1 and 3) and induced (2 and 4) Gem9 cells for 1 or 7 days. (F) Quantification of percentage of aneuploid cells after eight weeks in uninduced Gem9, induced Gem9 or induced Gem9 transfected with CKIε or Cdc7 cDNA cells detected in metaphase spread analysis. Values presented are means ± SD. **P ≤ 0.01.