This GRC will focus on how microbes and cancer cells utilize membrane-bound efflux pump systems to export antimicrobial or anticancer agents after they enter the target microbe or transformed cell. These efflux systems can singularly or in concert with other resistance mechanisms result in clinical failure of antibiotics and anti-cancer drugs respectively. Understanding their structure, mode of drug recognition and export, and their genetic regulation, is crucial for understanding how microbes and cancer cells develop multi-drug resistance, and for designing strategies to overcome these worrisome clinical problems. This field of study actually had one origin in the field of cancer biology, since the first drug efflux system was described by Victor Ling in tumour cells that had the capacity to export anti-tumour agents through the P-glycoprotein. The other major influence on the field was the early studies of Stuart Levy on tetracycline efflux, which revolutionized the field of antibiotic resistance. These two individuals are the Keynote Speakers on the first evening. Accordingly, this conference will concern itself with the science underlying how cancer treatments can be impacted by drug efflux, and how antibiotic efflux affects resistance. In particular, given evolutionary and/or mechanistic relationships between multidrug efflux in these two disciplines, we believe that it is time the discrete groups of researchers pursuing these two disciplines met and compared notes. It is therefore anticipated that this conference will contribute significantly to the dissemination of the latest information regarding mechanisms of drug resistance. This knowledge should promote the development of novel inhibitors or strategies that could counteract the contribution of efflux to drug resistance.