Fig. 4. Isoflurane sensitizes colon cancer HT29 cells (low caveolin-1 [Cav-1] expressing) to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis, but Cav-1 overexpression effectively protects against TRAIL. HT29-Cav-1 cells are sensitized to isoflurane exposure, resulting in increased DNA fragmentation with increased isoflurane concentrations (n = 6 for all groups except basal and 0.6%, which was n = 9) (A ). Stable HT29 cells expressing enhanced green fluorescent protein (HT29-GFP) and caveolin-1 (HT29-Cav-1) cells were cloned (n = 4) (B ). Real-time polymerase chain reaction revealed that HT29-Cav-1 cells had nearly a 2.5-fold increase in the antiapoptotic gene BCL2 6 h after a 30-min exposure to isoflurane (n = 4) (C ). Isoflurane continued to sensitize HT29-GFP cells to TRAIL-induced apoptosis over 2 h. However, HT29-Cav-1 cells showed significant protection against TRAIL at all time points. These results were confirmed via Western blot analysis for Cl-caspase 3 and caspase 3 activity, which revealed enhanced protection in HT29-Cav-1 cells (n = 5 for all groups) (D, E, and F ). *P < 0.05; **P < 0.01; ***P < 0.001.