C-MYC-ASSOCIATED GENOMIC INSTABILITY OF THE DIHYDROFOLATE-REDUCTASE LOCUS IN-VIVO

c-Myc overexpression is associated with the locus-specific amplificati on and rearrangement of the dihydrofolate reductase (DHFR) gene. This has been shown in lymphoid and nonlymphoid cell lines. Furthermore, c- Myc-dependent DHFR gene amplification occurs independent of species or igins; it has been described in rat, hamster, mouse, and human cell li nes. Here, we report on c-Myc-dependent amplification of the DHFR gene in vivo, using an animal model of c-Myc-dependent neoplasia, the mous e plasmacytoma.