Leukemia L1210Leukemia P388Leukemia Virus, MurineLeukemia, ExperimentalMoloney murine leukemia virusLeukemia L5178LeukemiaCell LineTrimetrexateTumor Cells, CulturedPteroylpolyglutamic AcidsLeukemia, Myeloid, AcuteFolic Acid AntagonistsCell Line, TumorAKR murine leukemia virusFriend murine leukemia virusHL-60 CellsDrug ResistanceAbelson murine leukemia virusMethotrexateLungAntineoplastic AgentsCell DivisionCell SurvivalLeukemia, LymphoidLeukemia, MyeloidLeukemia, Lymphocytic, Chronic, B-CellBase SequenceMolecular Sequence DataRetroviridae InfectionsLeukemia, Myelogenous, Chronic, BCR-ABL PositiveDoxorubicinLeukemia, Monocytic, AcuteCell Line, TransformedApoptosisK562 CellsRauscher VirusGene Expression Regulation, LeukemicCell DifferentiationLeukemia, T-CellStructure-Activity RelationshipRNA, MessengerMice, Inbred AKRPrecursor Cell Lymphoblastic Leukemia-LymphomaLeukemia, Promyelocytic, AcuteRetroviridaeTransfectionLung NeoplasmsLeukemia, Megakaryoblastic, AcuteLeukemia, B-CellXenotropic murine leukemia virus-related virusNeoplasm ProteinsDrug Screening Assays, AntitumorLung DiseasesMink Cell Focus-Inducing VirusesAmino Acid Sequence