FIG 6.

Ca²⁺ and K⁺ fluxes are sufficient to activate bacterial internalization. LLO-deficient (Δhly) L. monocytogenes bacteria (MOI of 20) were incubated with HepG2 cells with or without 1 μM ionomycin (Io) and/or 10 μM nigericin (Ni) in the indicated cell culture media. Bacterial internalization was measured by quantitative fluorescence microscopy and expressed relative to bacterial internalization in standard medium without ionophores. Results are expressed as the means ± SEM of at least three independent experiments (**, P < 0.01).