Fig. 3. Effects of antibody ligation of CD9 on the activation of caspase-3 and MAPK activity. (A) MKN-28 cells were incubated with 50 µg ml^–1 ALB6 or isotype-matched mouse IgG1 for the indicated periods. The adherent cells were harvested and subjected to immunoblots with anti-caspase-3 antibody. The arrow indicates the procaspase-3. The arrowhead indicates the cleaved caspase-3. (B) Annexin-V staining of the ALB6-treated MKN-28 cells is shown. MKN-28 cells were incubated with 50 µg ml^–1 ALB6 alone (left, shaded bars) or with ALB6 plus 50 µM ZVAD-FMK for 24 hours (right, shaded bars). Open bars show the staining of control cells. (C) MKN-28 cells were serum-starved for 24 hours, and then incubated with 50 µg ml^–1 ALB6 or isotype-matched mouse IgG1 for the indicated periods. The total cell lysates were analysed by immunoblotting with the indicated antibodies. Each figure shows representative data from four similar experiments.