(A) Effect of overexpression of mepR on mepA expression. Lane 1, SA-K2068-P; lane 2, SA-K2068-R; lane 3, SA-K1748-P; lane 4, SA-K1748-R. The negative effect of MepR on mepA expression is clearly evident. (B) Expression of mepRAB. Lane 1, S. aureus NCTC 8325-4; lane 2, SA-K2068; lane 3, SA-K1712; lane 4, SA-K1748.