ABCB1 and colonic neoplasm: The intracellular accumulation of [3H]-paclitaxel was significantly lower in the ABCB1-overexpressing SW620/Ad300 colon cancer cells compared to the parental SW620 cells, indicating that the overexpression of the ABCB1 transporter increases the efflux of the substrate, [3H]-paclitaxel (Figure 6B).