[Interferon]

Interferon (IFN) has anti-cell-proliferative activities. Some of the interferon-stimulated gene (ISGs) products have important roles for controlling cell proliferation and cell differentiation. Candidates for that kind of ISGs involve PKR, IRF-1, IRF-2, 2'5' OAS, RNaseL, and ICSBP. The PKR phosphorylate eIF2 alpha that leads to blocking of protein synthesis, mediates signal transduction via NF-kappa B and/or probably IRF-1, and is also involved in apoptosis. IRF-1 leads to apoptosis to prevent malignant transformation when a cell undergoes initial oncogene activation, and controls cell proliferation by balancing with IRF-2. 2'5' OAS and RNaseL system also has possibilities to have those roles. ICSBP, one of the IRF family, has new findings from the knock-out mouse. The mouse developed a hematopoietic abnormality which looks very similar to human chronic myelogenous leukemia, indicating ICSBP has important roles in proliferation and differentiation of hematopoietic stem cells.