FIG 8.
Cytotoxicity in established cell lines as a function of PSM production. MC3T3-E1 or RAW 264.7 cells were exposed to CM from cultures of LAC, UAMS-1 (U1), their isogenic αpsm mutants (Δpsmα), and complemented psm mutants (ΔpsmαC). Viability was assessed after 24 h using Invitrogen Live calcein-AM staining. Results of calcein-AM staining are reported as the average mean fluorescence intensity (MFI) ± standard deviation. *, statistical significance compared to the results observed with the isogenic parent strain; **, statistical significance compared to the results observed with the isogenic psm mutant.