Figure 2

Schematic model of development of anticancer drug resistance due to altered expression of transporters. SLC transporters (OCTs, OATs, CTR, and OATPs in green open ovals) may take up anticancer drugs into the cancer cells, while some ABC transporters (MDR1, MRP1, MRP3, and BCRP in blue open ovals) may extrude them. In addition, certain SLC transporters (PEPTs, LATs, and ATA1 in yellow open ovals) mediate the uptake of nutrients (e.g., amino acids and peptides) into cancer cells for their survival. The decreased expression of SLC transporters (black bold arrow) responsible for drug uptake or/and the increased expression of ABC transporter (purple bold arrow) for drug efflux make the cancer cells more resistant to anticancer drugs. The increased expression of SLC transporters (blue bold arrow) responsible for nutrient uptake may also cause more resistant to anticancer drugs as the cancer cells have an advantage of survival from limited nutrient supply.