Figure 2.

Apoptosis induced by H₂O₂. (a) H₂O₂-induced DNA fragmentation in ESCM. Wild-type and MEKK1−/− ESCM were treated with either 0.01 or 0.1 mM H₂O₂ for 6 h in the presence or absence of either the vehicle (DMSO 0.1%), PD98059 (50 μM), SB 203580 (10 μM), or anti-TNFα antibody (5 μg/ml, purified goat anti-mTNFα IgG; Research and Diagnostic Antibodies, Berkeley, CA). (b) H₂O₂-induced apoptotic cell death in ESCM evaluated by TUNEL staining. Wild-type and MEKK1−/− ESCM were treated with either 0.01 or 0.1 mM H₂O₂ for 6 h. Five hundred nuclei of cardiac myocytes costained with Hoechst 33258 were counted and the number of TUNEL positive cells was presented as a percentage from three independent experiments (mean ± SEM). *, P < 0.05 vs. each corresponding control.