we propagate norfloxacin-resistant strain, LTB4-R, through sequential propagations of norfloxacin-sensitive LTB4 in TSB broth medium with norfloxacin. LTB4-R had 128-fold minimum inhibitory concentrations (MIC) of LTB4-S. To profile the differential protein expression between LTB4-R and LTB4-S, tandem mass tag (TMT)-based quantitative proteomics method was adopted.