We found that fidarestat decreases growth of CRC cells and the expression of drug transporter proteins such as multidrug resistance protein 1 (MDR1 or Pgp-1 or ABCB1), multidrug resistance-associated protein 1 (MRP1 or ABCC1) and ATP-binding cassette subfamily G member 2 (ABCG2), which would increase the cytotoxic effects of DOX towards CRC cells. Here, ABCB1 is linked to colorectal carcinoma.