FIG. 1.

ompB (ompR and envZ) mutants are defective or highly reduced for Sif formation. Induction of Sif formation in HeLa cells by the Salmonella strains listed in Table 1 was determined at 6 h postinvasion. This graph represents results from one of four experiments where cells (100 for each strain) infected by each S. typhimurium strain tested were evaluated for Sif formation at 6 h postinvasion. Values are given as the percentage of infected cells containing Sifs. The dashed line provides a reference for Sif induction by wild-type SL1344.