Despite the fact that most of them may be repressed in CRC tumors, it has been shown that, when expressed in vitro, these efflux pumps can confer CRC cell resistance to a wide variety of cytostatic agents, such as cisplatin (MRP2), doxorubicin (MRP1 and MRP3), and etoposide (MRP1 and MRP3). The gene discussed is MSH3; the disease is colorectal carcinoma.