Reoxygenation-induced premature senescence in Fancc^–/– BM cells. (A) Reoxygenated Fancc^–/– LTBMC cells exhibited increased SA-β-gal activity. The hematopoietic cells harvested from a 2-week LTBMC were stained for SA-β-gal activity. (B) The percentage of the cells stained positive for SA-β-gal was quantified by counting a total of 1000 cells in random fields on a slide. The data represent the mean ± SD. *Statistical significance between reoxygenated WT and Fancc^–/– samples at P < .05. (C) Reoxygenated Fancc^–/– LTBMC cells accumulated high levels of oxidative DNA damage. DNA strand breaks were analyzed by a single-cell gel electrophoresis (comet) assay, in which nuclei and comet images visualized by SYBR Green staining. Shown are representative images of the comet assays. (D) DNA damage quantified by determining the comet tail movement (increasing values represent increasing amounts of DNA damage). The mean tail moment of the WT without treatment (Control) is expressed as 100%. For each treatment, 30 cells were scored for tail moment from random sampling. Data reflect means ± SD of 3 independent experiments performed. *Statistical significance between reoxygenated WT and Fancc^–/– samples at P < .05.