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Actinomycin D stimulation of teratoma cell adhesion
In cultured mouse teratoma cells, actinomycin D has been shown to stimulate glutamine synthetase (GS) specific activity with a concomitant increase in intercellular adhesion. Cultured mouse teratoma cells were preincubated for 24 hours with 5 ug/ml actinomycin D. They were then dissociated and incubated for 1 hour on a gyratory shaker. The decrease in single cell number, as determined with an electronic particle counter, was used to calculate the percent adhesion. The GS specific activity of these cells was then determined by an assay involving the glutamyltransferase reaction. It was found that the actinomycin D treated cells showed a 31.4 ± 9. 9% [mean ± standard error (S.E.)] increased intercellular adhesion and a 53+ 17% increase in GS specific activity. The increased adhesiveness of these cells may be due to the stimulated GS specific activity and subsequent synthesis of L-glutamine, which has been shown by Oppenheimer et al. (1969) and Oppenheimer (1973) to be required for teratoma intercellular adhesion. They suggest that the L-glutamine is required for the synthesis of complex cell surface carbohydrates involved in intercellular adhesion of teratoma cells.