Caspase activation by GW1843 in the presence and absence of Ac-DEVD-CHO. Cells were treated for the indicated times with 8 nmol/L GW1843 alone (▪) or in combination with 50 μmol/L Ac-DEVD-CHO (•). Aliquots were collected and assayed for caspase 3–like activity with Ac-DEVD-AMC as the substrate (solid lines) or ICE-like activity using Ac-YVAD-AMC as the substrate (dashed lines). Assays were performed as described in Materials and Methods. The data in these plots are from a representative experiment from three separate determinations.