However, as the loss of Abcc5 in rodents leads to a clear neurobiological phenotype, it would be prudent to not use ABCC5 inhibitors to treat multidrug resistant tumours in humans before the physiological substrate and function of ABCC5 is thoroughly characterised, as our data suggest that the inhibition of ABCC5 in the brain may lead to unexpected neurological side-effects. This evidence concerns the gene ABCC5 and neoplasm.