Since the discovery of its role as a drug efflux pump in multidrug resistant tumour cells in 1976,1 there has been an on-going search for potent and selective inhibitors of P-glycoprotein, which might be used for the treatment of multidrug resistance (MDR) – one of the major obstacles for a successful cancer chemotherapy.2 Likewise the anti-target property of P-glycoprotein is significant, especially with respect to its importance for the pharmacokinetics of compounds being substrates of this xenobiotic efflux pump. This evidence concerns the gene ABCB1 and neoplasm.