Fig. 5.

Effects of F. tularensis on XIAP, calpastatin and calpain. Neutrophils were left untreated, were infected with F. tularensis or were treated with STS as indicated. Immunoblots of cell lysates were probed to detect apoptosis regulatory factors or β-actin, and calpain activity was measured in whole cells using a fluorogenic substrate. a LVS infection impairs XIAP degradation by calpain. b LVS differentially influences calpain and calpastatin isoforms in neutrophils. In each case, the immunoblots are representative of ≥3 independent determinations. c Relative calpain activity in freshly isolated PMNs compared with cells that were treated with STS for 12 h or incubated for 24 h in the presence and absence of LVS. Data are the mean ± SD of 3 independent experiments. * p < 0.05; ** p < 0.01.