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 AgentsCell DivisionCell SurvivalLeukemia, LymphoidLeukemia, MyeloidLeukemia, Lymphocytic, Chronic, B-CellMolecular Sequence DataBase SequenceRetroviridae InfectionsLeukemia, Myelogenous, Chronic, BCR-ABL PositiveDoxorubicinLeukemia, Monocytic, AcuteCell Line, TransformedK562 CellsApoptosisRauscher VirusCell DifferentiationGene Expression Regulation, LeukemicLeukemia, T-CellStructure-Activity RelationshipRNA, MessengerMice, Inbred AKRPrecursor Cell Lymphoblastic Leukemia-LymphomaLeukemia, Promyelocytic, AcuteRetroviridaeTransfectionMice, Inbred BALB CLeukemia, Megakaryoblastic, AcuteLeukemia, B-CellAmino Acid SequenceXenotropic murine leukemia virus-related virusMice, Inbred StrainsNeoplasm ProteinsMink Cell Focus-Inducing VirusesFlow CytometryDrug Screening Assays, AntitumorDNA, ViralCells, Cultured