CASP3 and infection: Though remarkably high cytoplasmic caspase-3 and/or -7 activity was recorded in HeLa cells upon Lm infection, particularly in presence of TNF-α, the cells stayed viable according to nuclear morphology, cytoskeleton organization, plasma membrane integrity and mitochondrial metabolization rate, at least at the low multiplicities of infection (MOI ≤ 1) used in this study.