However, the IC50 values of 5-FU and TSA, which are not substrates of P-gp, were comparable between PT and OR CRC cells, except those of 5-FU in HT29/OR and SW480/OR CRC cells, indicating that P-gp may be partially involved in oxaliplatin resistance in OR CRC cells. This evidence concerns the gene PGP and colorectal carcinoma.