A. Representative images for fragile telomeres using the CO-FISH assay. Lagging strands (C-probe) and leading strands (G-probe) were marked with green PNA probes and red LNA probes, respectively. White circles and arrows indicate "smeary" or "doublet" telomeric signals, respectively. Quantification of fragile telomeres is shown on the right as the percentage of total telomeres counted (n=932-1073). Comparison of fragile to non-fragile telomere percentage was performed using Χ2-test. Data information: All scale bars: 5 μm. Data are shown as mean ± SD. 