Effect of PMA on the expression of PGI2-R, PF4, and GPIIb mRNA in HEL, NS-Meg, and CMK11-5 cells. PMA was added at the initiation of culture and cells harvested at the indicated times were examined by Northern analysis. The figure shows the representative results from triplicate experiments repeated twice. PMA enhanced PGI2-R expression in all of these cell lines. The time and intensity of maximum PGI2-R expression was as follows: HEL, 48 hours (threefold), NS-Meg, 48 hours (fivefold), and CMK11-5, 72 hours (eightfold). PMA enhanced the expression of GPIIb mRNA in these cell lines and that of PF4 mRNA in HEL cells. The controls were the cells cultured without PMA. They yielded no enhancement of PGI2-R for the entire culture periods except a little enhancement in HEL at 48 hours (48-hour controls are shown). All of the PMA-stimulated expressions were significantly different from respective control expressions in all of these cell lines (P < .01).
