FIG. 7.

PARP cleavage of mouse fibroblasts A31 after TRAIL and FasL treatment. A31-Neo and A31-E5 were serum starved and apoptosis was induced by either 500 ng of TRAIL or 50 ng of FasL/ml as described in Materials and Methods. Then, 50 μg of each protein extract was separated by SDS-PAGE and immunoblotted with antibodies detecting PARP. (A) In A31-Neo cells, cleavage starts 2 h after the addition of TRAIL and increases to a constant level at 4 and 8 h, whereas no significant cleavage can be detected in the A31-E5 cells. (B) Upon addition of FasL both cell lines show PARP cleavage that starts after 2 h and steadily increases until the end of the experiment.