Analysis of radial chromosome positioning in quiescent cell nuclei. Histograms displaying chromosome positions in primary human quiescent fibroblast nuclei. The 50 to 70 nuclei per chromosome were subjected to erosion analysis, which divides each nucleus into five concentric shells of equal area, with shell 1 being the most peripheral shell, and shell 5 being the most interior shell [4–6, 9]. The percentage of chromosome signal measured in each shell was divided by the percentage of 4',6-diamidino-2-phenylindole (DAPI) signal in that shell. Bars represent the mean normalized proportion (percentage) of chromosome signal for each human chromosome. Error bars represent the standard error of mean (SEM).