Caspase-3-deficient and -proficient MCF-7 cells were stably transfected with the above-described expression constructs by using the SuperFect reagent (QIAGEN). Forty hours posttransfection, cells were trypsinized and reseeded in selection medium containing 600-μg/ml concentrations of the appropriate antibiotic. Individual clones were picked and further cultured in 200-μg/ml concentrations of the appropriate antibiotic. To exclude the introduction of mutations in caspase-10 during the generation of the stable clones, the cDNAs encoded by the plasmid were reisolated from the single clones and sequenced. No mutations were found in the clones used.