Figure 6

Src enhances caspase-7 activity in vitro and in cells. (a) Phosphorylation of caspase-7 by Src increases caspase-7 activity. An in vitro kinase assay was performed using Src and a Wt-caspase-7 (0.8 μg) or Mut-caspase-7 (0.8 μg) protein. The reaction was then incubated with Wt-caspase-9 for 1 h at 32 °C and caspase-7 activity was detected at various time points as described in ‘Materials and Methods’. Data are shown as means±S.D. from triplicate experiments. The asterisks indicate a significant enhancement in caspase-7 activity (**P<0.01, ***P<0.001). (b) 293T cells were transiently transfected with HA-mock, Wt-myc-caspase-7 or Mut-myc-caspase-7 and at 24 h after transfection, cells were harvested. The level of Myc was detected by western blotting and caspase-7 activity was detected at various time points. Data are shown as means±S.D. from triplicate experiments. The asterisks indicate a significant enhancement in caspase-7 activity (**P<0.01, ***P<0.001). (c) 293T cells were transiently co-transfected with HA-mock/His-Src and Wt-myc-caspase-7/Mut-myc-caspase-7 and at 24 h after transfection, cells were harvested. His and Myc were detected by western blot using specific antibodies. Caspase-7 activity is shown as means±S.D. from triplicate experiments. The asterisks indicate a significant enhancement in caspase-7 activity (**P<0.01)