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pubmed:abstractText |
Ran (Ras-related nuclear protein), a Ras family GTPase, is involved in multiple cellular functions, including the regulation of DNA replication, cell cycle progression, nuclear structure formation, RNA processing-exportation, and nuclear protein importation. Ran(+/-) embryonic stem (ES) cells were produced in an attempt to generate Ran null mutant mice. Even after an extremely large number of blastocyst injections, no Ran(+/-) chimeric mice could be generated. Ran(+/-) ES cell-derived fibroblasts showed reduced Ran protein expression, and manifested augmented nuclear abundance of AP-1 factors (c-Jun and c-Fos) upon cytokine stimulation. Our experiments demonstrated that intracellular Ran protein levels controlled the nuclear presence of certain transcription factors, such as c-Fos and c-Jun.
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