caa a22 4500 465820808 CHVBK 20180323112135.0 cr unu---uuuuu 170327e19900301xx s 000 0 eng 10.1007/BF01233041 doi (NATIONALLICENCE)springer-10.1007/BF01233041 Isfort Robert Miami Valley Laboratories, Genetic Toxicology Section, Human and Environmental Safety Divison, The Procter and Gamble Company, P.O. Box 398707, 45239-8707, Cincinnati, Ohio aut Frequency and mechanisms of factor independence in IL-3-dependent cell lines [Elektronische Daten] [Robert Isfort] Interleukin-3 (IL-3) -dependent cell lines were tested for spontaneous mutation frequency with respect to two markers, growth factor-independent growth and 8-azaguanineresistant growth. The mutation frequency for the growth factor-independent growth was approximately equal to that of 8-azaguanine-resistant growth. Investigation of the growth factor-independent phenotypes indicated that at least two different mechanisms for growth factor independence existed. One mechanisms was the activation of the IL-3 gene by mutation resulting in the constitutive expression of IL-3 and autocrine regulated growth. A second mechanisms results in IL-3-independent growth in a manner in which (1) constitutive tyrosine kinase activity was not seen and (2) c-myc transcription was constitutively activated. Interestingly, in these cells both the tyrosine phosphorylation and c-myc transcriptional pathways are still activatable following IL-3 stimulation. At present, the exact nature of the mutation that results in this phenotype is not known. Plenum Publishing Corporation, 1990 Somatic Cell and Molecular Genetics Kluwer Academic Publishers-Plenum Publishers 16/2(1990-03-01), 109-121 0740-7750 16:2<109 1990 16 11188 https://doi.org/10.1007/BF01233041 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01233041 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Isfort Robert Miami Valley Laboratories, Genetic Toxicology Section, Human and Environmental Safety Divison, The Procter and Gamble Company, P.O. Box 398707, 45239-8707, Cincinnati, Ohio aut NATIONALLICENCE 773 0- Somatic Cell and Molecular Genetics Kluwer Academic Publishers-Plenum Publishers 16/2(1990-03-01), 109-121 0740-7750 16:2<109 1990 16 11188 Metadata rights reserved Springer special CC-BY-NC licence nationallicence SWISSBIB 465820689 BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer