Effect of RECQ1 depletion on spontaneous or oxidative stress induced apoptosis.

HeLa cells were siRNA treated for 48 h, and then incubated in complete medium for 24 h. Cells were either untreated or incubated with 400 µM H₂O₂ for 3 h in serum free medium, washed, and allowed to recover in complete medium for 21 h. Panel A, Enrichment of the cytoplasmic histone-associated-DNA fragments that are indicative of an ongoing apoptosis in cells with the indicated siRNA oligonucleotides. Samples were analyzed in duplicates, and data points represent the mean of three independent experiments; bars denote SD. Panel B, immunoblotting analysis of the PARP cleavage in control or RECQ1 siRNA treated HeLa cells either untreated or exposed to 400 µM H₂O₂.