Conversely, CRC cells can increase drug efflux by overexpression of ATP-binding cassette (ABC) transporters, such as P-glycoprotein (PGP, also known as multidrug resistance protein 1 or MDR1), breast cancer resistance protein (BCRP), and MDR-associated proteins (MRP1, MRP2) [41]. This evidence concerns the gene ABCG2 and colorectal carcinoma.