@article{oai:niigata-u.repo.nii.ac.jp:00006680,
 author = {Kato, Chihomi and Natsuno, Tetsuya and Saito, Kazuko},
 issue = {4},
 journal = {Acta medica et biologica, Acta medica et biologica},
 month = {Mar},
 note = {6-Mercaptopurine (6-MP) resistant strains of L1210 v/c murine leukemic cells were obtained in vivo 6-MP treatment of a DBA/2 mouse inoculated with sensitive L1210 cells. In one of these 6-MP resistant strains, double minutes (DMs) were found in 12% of the metaphase cells, the number of DMs per cell ranging from 5 to 20. When these 6-MP resistant cells were subcultured in 6-MP free medium for 20 months, only 2% of the cells had DMs ranging from 1 to 5 per cell. The decrease of DMs in number and appearance rate was accompanied by a lowering of the maximum allowable concentration (MAC) of 6-MP necessary to induce resistance in the cells from 1 μg to 0.1 μg/ml. These observations suggest that 6-MP resistance in L1210 cells is the result of an unknown gene amplification.},
 pages = {111--116},
 title = {Double minute chromosomes in a 6-MP resistant mouse leukemia L1210 cell line},
 volume = {34},
 year = {1987}
}