Fig. 1.

Stx induces apoptosis. (A) THP1 cells were treated with or without 50 μM Z-VAD-fmk. After 30 min, the cells were treated with 100 pg/ml Stx1 for 24 h then the cells were stained with PI. PI-positive cells were observed under the fluorescent microscope and counted with a flow cytometer. The percentage of PI-positive cells is indicated at the bottom. Bar: 25 μm. (B) THP1 cells were treated with 1 ng/ml Stx1, Stx2 or 2 μg/ml tunicamycin (TM) for the indicated periods. Whole cell lysates were analyzed by Western blotting with the indicated antibodies. The arrows show cleaved caspase 3 and PARP. (C and D) THP1 cells were treated with the indicated doses of Stx1 (C) or Stx2 (D) for 6 h. Whole cell lysates were analyzed by Western blotting with the indicated antibodies. The arrows show cleaved caspase 3 and PARP.