title: Increased dihydrofolate reductase, double minutes and increased nucleolar activation in methotrexate-resistant HeLa cells.
mesh_terms: D002869:Chromosome Aberrations; D004351:Drug Resistance; D005784:Gene Amplification / Q000187:drug effects; D006367:HeLa Cells / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D006801:Humans; D008727:Methotrexate / Q000494:pharmacology*; D009697:Nucleolus Organizer Region / Q000648:ultrastructure*; D013762:Tetrahydrofolate Dehydrogenase / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D013762:Tetrahydrofolate Dehydrogenase; D008727:Methotrexate