Figure 3.

The effect of protease inhibitors on cockroach-mediated cell death (submerged 16HBE cells). (A) Addition of cockroach extract resulted in reduced cell viability in a dose-dependent manner. (B) Heat-inactivated cockroach extract (75 °C, 3 min), which completely abolishes proteolytic activity, does not affect cell viability when added at a high dose (50 µg/well). (C) Cell viability was unaltered by protease inhibitors added alone (at a 50 µM dose for 24 hr). (D) Cockroach extract (16.5 µg/well, 24 h) significantly elicited decreased cell viability that was rescued by co-administration of PE-BBI but not pLR-HL or GM (all added at a 50 µM dose). Data are presented as the mean ± SEMs (n = 6). * P < 0.05.