Figure 2.

Activation of caspases and subsequent cleavage of poly(ADP-ribose) polymerase (PARP) during PES-induced apoptosis in U937 cells. U937 cells were incubated at the indicated concentrations of PES for 24 h. (A) Western blot analysis of the effects of PES on the caspase activation and PARP cleavage in a dose-dependent manner. (B) In vitro assay for caspase-3, -8 and -9 activity using Asp-Glu-Val-Asp (DEVD)-pNA, Ile-Glu-Thr-Asp (IETD)-pNA and Leu-Glu-His-Asp (lEHD)-pNA as substrates, respectively. The released fluorescent products were measured. The data are shown as means ± SD of three independent experiments. ^*P<0.05 vs. control. PES, polyphenols from Korean E. supina.