Multidrug resistance-associated protein 1 (MRP1/ABCC1) is a member of the MRP subfamily of ATP-binding cassette (ABC) transporters. MRP1 is an integral membrane protein that contains an Mdr-like core, an N-terminal membrane-bound region and a cytoplasmic linker, and it is expressed in various cerebral cells, as well as in lung, testis and peripheral blood. Research studies show that overexpression of MRP1 facilitates the elimination of therapeutic agents from cancer cells and confers drug resistance in those patients. Research studies also show that elevated expression of MRP1 is a negative prognostic marker for breast cancer and small cell lung cancer, as the level of MRP1 is predictive of the response and toxicity of chemotherapeutic agents in those patients.
