The physiological relevance of drug transport remains unclear but animal studies have shown that engineered expression of MRP2 in implanted cancer cells confers resistance to cisplatin12 and in a small clinical study MRP2 expression levels in hepatocellular cancer patients correlated with a reduction in cisplatin-induced tumour necrosis suggesting that MRP2 is a potential determinant of multidrug resistance13. This evidence concerns the gene ABCC2 and cancer.