Activation of caspases and degradation of PARP and β-catenin protein by DATS treatment in U937 cells. Cells were treated with the indicated concentration of DATS for 48 h. (A) Cells were lysed and then equal amounts of cell lysates (30 μg) were separated on SDS-polyacrylamide gels and transferred to nitrocellulose membranes. Membranes were probed with the indicated antibodies. An ECL detection system was used for visualization of proteins. Actin was used as an internal control. (B) Cells grown under the same conditions as (A) were collected and lysed. Aliquots were incubated with DEVD-pNA, IETD-pNA, and LEHD-pNA for caspase-3, -8, and −9, individually, at 37 for 1 h. Released fluorescence products were measured. Each point represents the mean ± the SD of representative experiments performed at least three times. A Student’s t-test (*, p < 0.05 vs. untreated control) was used for analysis of statistical significance of the results.