Figure 6.

Caspase-3 cleavage activity in defined apoptosis in mouse thymocytes at the day of birth. Mouse thymocytes were treated for 2 h with dexamethasone (A), a mouse Fas monoclonal antibody (B), and etoposide (C) to induce apoptosis at the indicated concentrations. Cells were also treated for the indicated times (h) with UV irradiation (D). Caspase-3 activity was measured as relative fluorescence intensity based on the cleavage of the fluorogenic substrate acetyl-aspartyl-glutamyl-valyl-aspart-1-aldehyde-7-amino-4-trifluoromethyl coumarin. Caspase-3 activities in Smg GDS+/− thymocytes (open circles) and Smg GDS−/− thymocytes (closed squares) are shown. Untreated cells were primarily negative for the presence of active caspase-3.