[ATP-dependent glutathione conjugate export pump]

KCP4 cells are resistant to cisplatin and have a GS-X pump different from MRP. The GS-X pump was suggested to be involved in reducing the accumulation of cisplatin in KCP-4 cells. The expression of cMOAT was 4-to 6-fold higher in KCP-4 cells and two other cisplatin-resistant human cell lines. It is still not clear whether the cisplatin resistance in KCP-4 cells are attributed to cMOAT. Other members of the MRP/GS-X pump family have been reported. Amino acid sequence of EBCR of rabbit is 91% identical to that of human cMOAT. On the view of cancer chemotherapy, it is very important to understand the structure and function of GS-X pumps since they may be involved in not only drug resistance but also drug metabolism and side effects.