Variations in c-fos mRNA expression during serum induction and the synchronous cell cycle.
Induction of c-fos mRNA levels associated with the stimulation of growth by fetal bovine serum following quiescence was examined in three cell types following brief (24 h) serum starvation. Starved NIH-3T3 and HeLa S3 cells experienced c-fos mRNA induction 20-30 min after addition of serum. In contrast, Swiss-3T3 cells expressed c-fos constitutively following serum starvation. The pattern of oncogene expression coincided with the level of quiescence of each cell line prior to induction. Serum inductions of c-fos expression was dependent upon the response of each cell line to serum starvation, c-fos expression was also examined in HeLa S3 cells that had been separated into sequential cell cycle phases by centrifugal elutriation, c-fos expression peaked during the earliest part of the synchronous G1 phase. The amount of c-fos mRNA measured was approximately twice that found during other cell cycle phases. This suggests that, in addition to its role during the transition from quiescence, the c-fos gene product may play a regulatory role during the earliest part of G1 phase of the continuous cell cycle.
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Department of Pathobiology, College of Veterinary Medicine, Auburn University, AL 36849-5519.
Kung
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Wu
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Young-White
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D000818:Animals; D001769:Blood; D002453:Cell Cycle; D002460:Cell Line; D015342:DNA Probes; D005347:Fibroblasts; D015870:Gene Expression; D006367:HeLa Cells; D006657:Histones / Q000235:genetics; D006801:Humans; D007399:Interphase; D007700:Kinetics; D051379:Mice; D009693:Nucleic Acid Hybridization; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016760:Proto-Oncogene Proteins c-fos; D016271:Proto-Oncogene Proteins c-myc; D016283:Proto-Oncogene Proteins p21(ras); D012333:RNA, Messenger / Q000096:biosynthesis*
D015342:DNA Probes; D006657:Histones; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)