ABCB1 and cancer: These transporters include the ATP-binding cassette (ABC) proteins ABCB1 (P-gp, MDR1) and ABCC2 (MRP2), which are efflux transporters involving doxorubicin disposition [4,6,7], and the solute carrier SLC22A16, an organic cation influx transporter that mediates doxorubicin uptake in cancer cells [8].