Isopentenyladenosine Stimulates and Inhibits Mitosis of Human Lymphocytes Treated with Phytohemagglutinin

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Science  25 Jul 1969:
Vol. 165, Issue 3891, pp. 400-402
DOI: 10.1126/science.165.3891.400


The plant cytokinin isopentenyladenosine, a component of yeast and mammalian transfer ribonucleic acid, is both a potent inhibitor and stimulator of DNA synthesis, transformation, and mitosis of the phytohemagglutinin-stimulated lymphocyte. The stage of the cell cycle and the concentrations used are critical for these effects. The addition of isopentenyladenosine within the first 12 hours after phytohemagglutinin at a concentration above 10-6 molar results in inhibition, while lower concentrations (between 10-7 and 10-6 molar), added at 24 hours or later, have a stimulatory effect.

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