Leukemia L1210Leukemia: A progressive, malignant disease of the blood-forming organs, characterized by distorted proliferation and development of leukocytes and their precursors in the blood and bone marrow. Leukemias were originally termed acute or chronic based on life expectancy but now are classified according to cellular maturity. Acute leukemias consist of predominately immature cells; chronic leukemias are composed of more mature cells. (From The Merck Manual, 2006)Leukemia, Experimental: Leukemia induced experimentally in animals by exposure to leukemogenic agents, such as VIRUSES; RADIATION; or by TRANSPLANTATION of leukemic tissues.Leukemia, Myeloid, Acute: Clonal expansion of myeloid blasts in bone marrow, blood, and other tissue. Myeloid leukemias develop from changes in cells that normally produce NEUTROPHILS; BASOPHILS; EOSINOPHILS; and MONOCYTES.Aminoacridines: Acridines which are substituted in any position by one or more amino groups or substituted amino groups.Adenosine Deaminase Inhibitors: Drugs that inhibit ADENOSINE DEAMINASE activity.Coformycin: A ribonucleoside antibiotic synergist and adenosine deaminase inhibitor isolated from Nocardia interforma and Streptomyces kaniharaensis. It is proposed as an antineoplastic synergist and immunosuppressant.Leukemia, Lymphocytic, Chronic, B-Cell: A chronic leukemia characterized by abnormal B-lymphocytes and often generalized lymphadenopathy. In patients presenting predominately with blood and bone marrow involvement it is called chronic lymphocytic leukemia (CLL); in those predominately with enlarged lymph nodes it is called small lymphocytic lymphoma. These terms represent spectrums of the same disease.Leukemia L5178: An experimental lymphocytic leukemia of mice.Ribonucleosides: Nucleosides in which the purine or pyrimidine base is combined with ribose. (Dorland, 28th ed)Sarcoma 180Leukemia, Lymphoid: Leukemia associated with HYPERPLASIA of the lymphoid tissues and increased numbers of circulating malignant LYMPHOCYTES and lymphoblasts.Leukemia, Myelogenous, Chronic, BCR-ABL Positive: Clonal hematopoetic disorder caused by an acquired genetic defect in PLURIPOTENT STEM CELLS. It starts in MYELOID CELLS of the bone marrow, invades the blood and then other organs. The condition progresses from a stable, more indolent, chronic phase (LEUKEMIA, MYELOID, CHRONIC PHASE) lasting up to 7 years, to an advanced phase composed of an accelerated phase (LEUKEMIA, MYELOID, ACCELERATED PHASE) and BLAST CRISIS.Leukemia Virus, Murine: Species of GAMMARETROVIRUS, containing many well-defined strains, producing leukemia in mice. Disease is commonly induced by injecting filtrates of propagable tumors into newborn mice.Drug Resistance: Diminished or failed response of an organism, disease or tissue to the intended effectiveness of a chemical or drug. It should be differentiated from DRUG TOLERANCE which is the progressive diminution of the susceptibility of a human or animal to the effects of a drug, as a result of continued administration.Mice, Inbred DBADNA, Neoplasm: DNA present in neoplastic tissue.Precursor Cell Lymphoblastic Leukemia-Lymphoma: A neoplasm characterized by abnormalities of the lymphoid cell precursors leading to excessive lymphoblasts in the marrow and other organs. It is the most common cancer in children and accounts for the vast majority of all childhood leukemias.Antineoplastic Agents: Substances that inhibit or prevent the proliferation of NEOPLASMS.Leukemia, T-Cell: A malignant disease of the T-LYMPHOCYTES in the bone marrow, thymus, and/or blood.Leukemia, Monocytic, Acute: An acute myeloid leukemia in which 80% or more of the leukemic cells are of monocytic lineage including monoblasts, promonocytes, and MONOCYTES.Cell Division: The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.Moloney murine leukemia virus: A strain of Murine leukemia virus (LEUKEMIA VIRUS, MURINE) arising during the propagation of S37 mouse sarcoma, and causing lymphoid leukemia in mice. It also infects rats and newborn hamsters. It is apparently transmitted to embryos in utero and to newborns through mother's milk.Leukemia, Hairy Cell: A neoplastic disease of the lymphoreticular cells which is considered to be a rare type of chronic leukemia; it is characterized by an insidious onset, splenomegaly, anemia, granulocytopenia, thrombocytopenia, little or no lymphadenopathy, and the presence of "hairy" or "flagellated" cells in the blood and bone marrow.Leukemia, B-Cell: A malignant disease of the B-LYMPHOCYTES in the bone marrow and/or blood.Leukemia Virus, Bovine: The type species of DELTARETROVIRUS that causes a form of bovine lymphosarcoma (ENZOOTIC BOVINE LEUKOSIS) or persistent lymphocytosis.Leukemia Virus, Feline: A species of GAMMARETROVIRUS causing leukemia, lymphosarcoma, immune deficiency, or other degenerative diseases in cats. Several cellular oncogenes confer on FeLV the ability to induce sarcomas (see also SARCOMA VIRUSES, FELINE).Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Structure-Activity Relationship: The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.Gene Expression Regulation, Leukemic: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in leukemia.Leukemia, Radiation-Induced: Leukemia produced by exposure to IONIZING RADIATION or NON-IONIZING RADIATION.Myeloid-Lymphoid Leukemia Protein: Myeloid-lymphoid leukemia protein is a transcription factor that maintains high levels of HOMEOTIC GENE expression during development. The GENE for myeloid-lymphoid leukemia protein is commonly disrupted in LEUKEMIA and combines with over 40 partner genes to form FUSION ONCOGENE PROTEINS.Leukemia P388: An experimental lymphocytic leukemia originally induced in DBA/2 mice by painting with methylcholanthrene.Kinetics: The rate dynamics in chemical or physical systems.Leukemia, Biphenotypic, Acute: An acute leukemia exhibiting cell features characteristic of both the myeloid and lymphoid lineages and probably arising from MULTIPOTENT STEM CELLS.