Fig. 7

Ser24–PP2Ac phosphorylation induces JNK phosphorylation and apoptosis. A Ser24-PP2Ac phosphorylation is required for the PP2Ac switch-related JNK activatory phosphorylations. αT3-1 or PC3 cells were transfected with either HA-PP2Ac or PP2Ac mutants (S24A, S24E) in PCDNA3 in serum strvation medium (0.1% FCS 16 h). The cells were then either stimulated with TPA (250 nM, 30 min) or left untreated. Next, the cells were harvested, and cell extracts were analyzed by Western blotting with the indicated Abs. The bar-graphs in the lower panels represent means ± SD, of 3 experiments. Significance of change from non-stimulated HA-PP2Ac control (time 0) is calculated. * p < 0.01, ** p < 0.05. B, C Ser24-PP2Ac phosphorylation is required for the PP2Ac switch-induced apoptosis. Serum starved αT3-1 or PC3 expressing HA-PP2Ac or mutated PP2Ac as described in panel (A), were TPA (250 nM, 48 h) stimulated or left untreated. TPA-induced cell death was detected by cleaved PARP1 (B) or TUNEL (C). The results shown represent means ± SD. Significance of change from HA-PP2Ac, non-stimulated control (NT) was calculated. * p < 0.01, ** p < 0.05