The multisubstrate nucleoside kinase of Drosophila melanogaster(Dm-dNK) can be expressed in human solid tumor cells and its unique enzymatic properties makes this enzyme a suicide gene candidate. In the present study,Dm-dNK was stably expressed in the CCRF-CEM and H9 T-lymphoblastoid cell lines. The expressed enzyme was localized to the cell nucleus and the enzyme retained its activity.