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. 2003 May;71(5):2724–2735. doi: 10.1128/IAI.71.5.2724-2735.2003

FIG. 6.

FIG. 6.

FIG. 6.

(A) Effects of Stx1 on caspase enzymatic activities in HeLa cells. Cells were incubated without or with Stx1(10 ng/ml) for the times indicated, and activities of caspases 3, 6, 8, and 9 were monitored with fluorescent substrates in microtiter plate format as described in Materials and Methods. (B) Effects of caspase inhibitors on Stx1-induced apoptosis in HeLa cells. Cells were preincubated with caspase inhibitors for 1 h, followed by incubation with Stx1 (10 ng/ml) for 4 h, where indicated. All caspase inhibitors were used at 20 μM. Lane1, no Stx1 or caspase inhibitor; lane 2, Stx1 only; lane 3, Stx1 plus general caspase inhibitor (Z-VAD-fmk); lane 4, Stx1 plus caspase-1 inhibitor (Z-YVAD-fmk); lane5, Stx1 plus caspase-2 inhibitor (Z-VDVAD-fmk); lane 6, Stx1 plus caspase-3 inhibitor (Z-DEVD-fmk); lane 7, Stx1 plus caspase-6 inhibitor (Z-VEID-fmk); lane 8, Stx1 plus caspase-8 inhibitor (Z-IETD-fmk); lane 9, Stx1 plus caspase-9 inhibitor (Z-LEHD-fmk). (C) Effects of caspase inhibitors on Stx2-induced apoptosis in HeLa cells. All caspase inhibitors were used at 20 μM. Lane1, no Stx2 (10 ng/ml) or caspase inhibitor; lane 2, Stx2 only; lane 3, Stx2 plus general caspase inhibitor (Z-VAD-fmk); lane 4, Stx2 plus caspase-1 inhibitor (Z-YVAD-fmk); lane5, Stx2 plus caspase-2 inhibitor (Z-VDVAD-fmk); lane 6, Stx2 plus caspase-3 inhibitor (Z-DEVD-fmk); lane 7, Stx2 plus caspase-6 inhibitor (Z-VEID-fmk); lane 8, Stx2 plus caspase-8 inhibitor (Z-IETD-fmk); lane 9, Stx2 plus caspase-9 inhibitor (Z-LEHD-fmk).