Resistance of tumors to multiple chemotherapeutic agents is often due to the MDR (Multiple Drug Resistance) gene. This gene encodes a protein that acts by which of the following mechanisms?
A.	As a transmembrane efflux pump for chemotherapeutic agents
B.	As a DNA repair molecule
C.	As an isoform of superoxide dismutase
D.	As a membrane stabilizer
Answer:A
Resistance of tumors to multiple chemotherapeutic agents is often due to the MDR (Multiple Drug Resistance) gene. This gene encodes a protein that acts by which of the following mechanisms?
A.	As a transmembrane efflux pump for chemotherapeutic agents B.	As a DNA repair molecule C.	As an isoform of superoxide dismutase D.	As a membrane stabilizer