Leukemia L1210Leukemia P388Leukemia Virus, MurineLeukemia, ExperimentalMoloney murine leukemia virusLeukemia L5178LeukemiaCell LineTrimetrexateTumor Cells, CulturedPteroylpolyglutamic AcidsLeukemia, Myeloid, AcuteFolic Acid AntagonistsAKR murine leukemia virusCell Line, TumorFriend murine leukemia virusHL-60 CellsDrug ResistanceAbelson murine leukemia virusMethotrexateAntineoplastic AgentsBase SequenceCell DivisionMolecular Sequence DataCell SurvivalPlasmidsLeukemia, LymphoidLeukemia, MyeloidLeukemia, Lymphocytic, Chronic, B-CellRetroviridae InfectionsLeukemia, Myelogenous, Chronic, BCR-ABL PositiveDoxorubicinLeukemia, Monocytic, AcuteCell Line, TransformedK562 CellsRauscher VirusApoptosisGene Expression Regulation, LeukemicStructure-Activity RelationshipLeukemia, T-CellCell DifferentiationRNA, MessengerTransfectionMice, Inbred AKRLeukemia, Promyelocytic, AcutePrecursor Cell Lymphoblastic Leukemia-LymphomaRetroviridaeAmino Acid SequenceCloning, MolecularGenetic VectorsLeukemia, Megakaryoblastic, AcuteLeukemia, B-CellDNA, ViralMutationXenotropic murine leukemia virus-related virusMink Cell Focus-Inducing VirusesNeoplasm ProteinsDrug Screening Assays, AntitumorTranscription, Genetic