Figure 4.

FTI induces activation of caspase 3 but not caspase 1. KNRK cells were treated with DMSO (control), 20 μM PD98059 (MEK inhibitor), 20 μM SCH56582 (FTI), or 20 μM SCH56582 plus 50 mM Z-DEVD-fmk (FTI + Z-DEVD-fmk) in 0.1% FCS medium. Cells were collected after 24 h, and caspase 3 and caspase 1 activities were measured as described in Materials and Methods by using the substrates Ac-DEVD-AMC and Ac-YVAD-AMC, respectively. At least 10,000 cells were examined in each assay.