Following 24 h incubation with 50 μg/ml 5-FU, we observed that the intracellular 5-FU levels are approximately two fold higher in the lysates of cells transfected with AQP9 compared with vectors (Figure 3, P=0.003), suggesting that the overexpression of AQP9 enhances 5-FU uptake into CRC cells. Here, AQP9 is linked to colorectal carcinoma.