title: Preliminary communications.
mesh_terms: D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D004351:Drug Resistance; D002955:Leucovorin / Q000494:pharmacology; D007940:Leukemia L5178 / Q000378:metabolism; D008727:Methotrexate / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism; D013997:Time Factors
chemical_list: D013762:Tetrahydrofolate Dehydrogenase; D002955:Leucovorin; D008727:Methotrexate