In order to characterize more precisely the effect of SP on B. cereus virulence we measured the production of caspase-1 by keratinocytes after infection with bacteria pretreated for 1 h with SPrev (control) or SP 10−6 M. As shown in Fig. 2A, after 30 min of infection, the production of caspase-1 by keratinocytes exposed to SP treated Bacilli rose significantly (+174±51%, P<0.05). This evidence concerns the gene CASP1 and infection.