DNA damage–induced apoptotic response is increased in FA-A cells. (A) Control (□) and 2 FA-A lymphoblast cell lines (▦, ▪) were exposed to different doses of UV radiation and left in culture for 12 hours. The percentage of dead cells was then measured by trypan blue dye exclusion. (B-C) Control and FA-A lymphoblasts were exposed to UV radiation (700 J/m2) and left in culture for 5 hours or treated with 50 nM MMC for 48 hours, and then apoptotic cell death was determined by an enzyme immunoassay method that quantifies the histone-associated DNA fragments present in the cytosol (B) or by Western blot with an antibody that recognizes both the full-length (112 kDa) and the cleavage fragment (85 kDa) of PARP protein (C). The levels of β-tubulin were determined to assure equal loading. A405, units of absorbance at 405 nm. Histograms represent the means ± SD of triplicate analyses.
