Fig. 4.

ATP or BzATP stimulates caspase-1 and caspase-3 activity in SMG cells from wild-type, but not P2X7R^−/−, mice. Dispersed SMG cell aggregates from wild-type and P2X7R^−/− mice were treated at pH 7 with 3 mM ATP, 0.3 mM BzATP, or vehicle for 3 h at 37°C. Cells were collected by centrifugation and caspase-1 (A) or caspase-3 (B) activity was quantified using fluorometric analysis, as described in materials and methods. Data represent means ± SE (n = 4), where *P < 0.05 indicates a significant difference from basal caspase activity, whereas #P < 0.05 and ##P < 0.01 indicate significant differences from ATP/BzATP-induced caspase activity in wild-type SMG. C: alternatively, SMG cell aggregates were treated at pH 7 with 0.3 mM BzATP, 3 mM ATP, 1 μM staurosporine, or vehicle for 24 h at 37°C. Cells were collected, and samples were subjected to immunoblot analysis using anti-caspase-1 or anti-caspase-3 antibody, as described in materials and methods. Blots represent 3 independent experiments with similar results.