Figure 4

Inhibition of PM/Scl-75 cleavage by caspase inhibitors. Jurkat cells were cultured for 1 hour at 37°C in the presence of four cell-permeable tetrapeptide caspase inhibitors: 2 μM (lanes 4, 6, 8 and 10) or 20 μM (lanes 5, 7, 9 and 11) inhibitors of caspase-1 (YVAD), caspase-3 (DEVD), caspase-8 (IETD) and caspase-9 (LEHD). Subsequently, cells were cultured for 8 hours in the presence of anti-Fas monoclonal antibody (α-Fas). Control extract from mock-treated Jurkat cells was loaded in lane 1. In lanes 2 and 3 extracts from control and apoptotic (8 hours anti-Fas mAb) Jurkat cells, respectively, were analyzed. Total protein extracts were analyzed by 10% SDS-PAGE and Western blotting with the anti-PM/Scl-75 rabbit serum. The positions of molecular mass markers are indicated in kDa at the right and the positions of the relevant polypeptides at the left. Filled arrowheads indicate full-length proteins, open arrowheads indicate cleavage products and the asterisk indicates cross-reactivity of the anti-PM/Scl-75 serum.