ATP Binding Cassette (ABC) transporters and their roles in cystic fibrosis, multiple drug resistance and the evolution of superbugsATP-Binding Cassette (ABC) transporters work as molecular pumps to transport substrates across cellular membranes. Represented in all organisms, ABC proteins are divided into two classes (i) exporters that mediate expulsion of unrelated substances across membranes and (ii) importers which function to allow nutrients into the cell. In both classes, ABC transporters use the energy of ATP to pump substrates into or out of the cell. Functional defects in ABC transporters play a role in at least 13 diseases, including cystic fibrosis, Stargardt disease, and age-related macular degeneration. Additional members of this family transport a variety of amphipathic compounds out of the cell, including anticancer drugs, contributing to the resistance of cancer cells to chemotherapy. While the multidrug resistance (MDR) phenomenon is becoming increasingly common, how cells become resistant to pesticides, antibiotics, and chemotherapeutic drugs is still a mystery. However, our understanding of the mechanism of transport not only allows us understand the selectivity mechanism in MDR but also allows us to manipulate these proteins for engineering and transport of natural products. Our current research focuses on bacteria's ability to acquire nutrients while defending against host factors of immunity, a dynamic interplay between a pathogen and its host.