L1210/TK-

L1210/TK− cells are thymidine kinase-deficient derivatives of the murine L1210 leukemia line, generated through selection from thymidine kinase-proficient parental L1210/0 cells^[1][2]. A related designation, L1210/BdUrd, was selected for growth in high concentrations of 5-bromodeoxyuridine and was likewise characterized as thymidine kinase deficient^[2]. These paired parental and deficient cells have been used to test how thymidine kinase determines sensitivity to substituted deoxyuridines and to distinguish nucleoside activation from effects on nucleotide metabolism, DNA synthesis, and glycoprotein biosynthesis; the model represents a laboratory-selected metabolic phenotype rather than a distinct leukemia subtype or independent disease of origin^[1][2].