Figure 7: Interaction between gemcitabine metabolism and efflux. dFdU is effluxed by ABCC transporters allowing for continued gemcitabine deamination, while inhibition of efflux could result in intracellular accumulation of dFdU inhibiting deamination and resulting in increased intracellular gemcitabine concentrations and cytotoxicity; dFdU=2,2-difluorodeoxycytidine (gemcitabine); dFdU=2,2-difluorodeoxyuridine (deaminated gemcitabine metabolite); MP=monophosphate; DP=diphosphate; TR=triphosphate; CDA=cytidine deaminases; DCTD=deoxycytidylate deaminases; RR=ribonucleotide reductase.