Role of Na+/H+-Antiporter in Growth Stimulation by Ha-ras
Expression of the transforming Ha-ras oncogene in MMTV-LTR-Ha-ras transfected 3T3 fibroblasts causes a growth factor independent intracellular alkalinization by a dimethylamiloride sensitive mechanism. The phenomenon is accompanied by a desensitization of the intracellular calcium mobilizing system to serum growth factors and an increase in the generation of inositol phosphates. Data are presented which support the assumption that the mobilization of intracellular Ca2+ occurs by a Na+-dependent mechanism. The results are discussed as indicating a constitutive activation of growth factor signal transduction by transforming Ha-ras. The exact sequences of events initiated by the oncogene, however, remains to be elucidated.
KeywordsInositol Phosphate Oncogene Expression Calcium Free Medium Intracellular Alkalinization Serum Growth Factor
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