FIGURE 7.

Presenilin-deficient MEFs show increased resistance to TNF-induced apoptosis. a, wild type and PS DKO MEFs were treated in the absence (Control) or presence of murine TNFα (50 ng/ml) and cycloheximide (CHX) (10 μg/ml) for 6 h. Cells were photographed using a phase-contrast microscope at ×40 magnification. b, WT and PS DKO MEFs were treated in the absence (Control) or presence of murine TNFα (50 ng/ml) and cycloheximide (10 μg/ml) for 4 h. Percentage of apoptotic cells showing annexin V positivity. The columns show the means ± S.E. (error bars) of the mean of three independent experiments; **, p < 0.01 (two-way ANOVA). c and d, wild type and PS DKO MEFs were treated in the absence (0 h) or presence of murine TNFα (40 ng/ml) and cycloheximide (10 μg/ml) for 2, 4, 6, or 8 h, as indicated. Cell lysates were probed by immunoblotting for levels of cleaved caspase 3 c and cleaved PARP d. Cell lysates were also probed for levels of β-actin to act as loading controls. Data are from one experiment representative of at least three independent experiments.