text: Wild-type enzymes and variants of CDA (<< Lys27Gln >> and Ala70Thr) and DCK (Ile24Val, Ala119Gly, and Pro122Ser) were expressed in and purified from Escherichia coli, and enzyme kinetic parameters were estimated for cytarabine ([[ Ara-C ]]), dFdC, and its metabolite 2',2'-difluorodeoxyuridine (dFdU) as substrates.