confers_resistance_to_antibiotic ciprofloxacin tetracycline confers_resistance_to_antibiotic marR Escherichia coli MarR with mutation associated with multidrug resistance Ecol_MarR_MULT antibiotic_resistance MarR is a transcriptional regulator and repressor for the expression of marA, itself an activator of the multidrug efflux pump AcrAB. Certain mutations in the marR gene are associated with increased resistance to drugs including tetracycline and ciprofloxacin through increased AcrAB activity. ARO:3003378