(A). Immunoblot analysis. Equivalent amounts of outer membrane (OM) protein of the rmlC mutant (rmlC), the rmlC complemented strain (rmlC/rmlC+), and the TolC overexpression strain (rmlC/tolC+) were separated, transferred to PVDF, and probed with anti-LtxA antibody. (B). Quantification of leukotoxin (LtxA). The integrated intensity of each band in panel A, which represents the relative protein level, was quantified using the ImageJ program. The membrane-bound leukotoxin found in the rmlC/tolC+ strain remained the same as the rmlC mutant. The signal intensity of the rmlC mutant was arbitrarily set as 1.0. (ns: nonsignificant)