Figure 3.

p25 formation requires activation of the mitochondrial death pathway. Left panels display representative Western blots, and center and right panels display quantitative analysis of p35 and p25, respectively, from three or more separate experiments (error bars represent the mean ± SEM). Density values for each band were first normalized to loading control and then to the zero time point. A, B, Cortical neurons were treated with camptothecin (campto) alone or with camptothecin plus 100 μm BAF (A) or campto plus 50 μm DEVD-FMK (B) for 8 and 16 h. Total cellular protein was subjected to Western blot and analyzed for p35 and p25 levels. Caspase inhibition with BAF or DEVD-FMK prevents production of p25 after DNA damage. C, D, Neurons from individual Bax (C) or Apaf-1 (D) -deficient embryos and from appropriate littermate controls were treated with camptothecin, and levels of p35 and p25 were analyzed by Western blot.