PGP and colorectal carcinoma: Multidrug resistance (MDR) is the main cause of chemotherapy failure and disease progression in colorectal carcinoma (CRC) patients.1,2 The mechanisms of MDR are varied and include increased drug efflux, reduced drug uptake, effects on membrane lipids, increased drug metabolism, changes in drug targets, inhibition of programmed cell death (apoptosis), induction of DNA damage repair and alterations of the cell cycle and associated checkpoints.3 Overexpression of ABC transporters, such as MDR1/P-gp, which limits the long-term effective use of chemotherapeutic drugs, is the main cause of MDR.4