... weretransformed into KY895 and then the strains were examined for growth, +, in the presence of different concentrations of thymidine in the medium. In the last column, LD100values are given (in ... deoxyribonucleosides; dT, deoxythymidine; dU, deoxyuridine; dC,deoxycytidine; dA, deoxyadenosine; dG, deoxyguanosine; hTK1, human thymidine kinase 1; HSV1-TK, Herpes simplex virus 1 thymidinekinase; LID region, ... cellu-lar kinases the triphosphorylated nucleoside analogsare incorporated into DNA and cause chain termin-ation and cell death [2]. Alternatively, they inhibit theDNA synthesizing machinery or initiate...