<prompt> How does MDR gene act?Block drug activationBlock intracellular DNA synthesisCause efflux of drugDNA repair inhibition  <response>: The multidrug resistance MDR gene encodes a protein that actively pumps drugs out of tumor cells. This gene confers resistance on a variety of antitumor drugs, including the antibiotics and plant-derived compounds. Tumor resistance to a given chemotherapeutic agent can often be overcome by the administration of multiple drugs. Ref: Sabel M.S. 2010. Chapter 44. Oncology. In G.M. Dohey Ed, CURRENT Diagnosis Treatment: Surgery, 13e. 