Effect of MK-801 on GPIIIa expression in MEG-01 cells. MEG-01 cells were incubated in the presence of the indicated compounds for 3 days. Results expressed as percentage of the increase in the median fluorescence intensity observed in the presence of PMA alone. Addition of the PKC inhibitor GF109203X (3 μmol/L) was used as a positive control and fluorescence intensity of samples not treated with PMA was subtracted from values obtained in the presence of PMA. Results indicated that 50 to 150 μmol/L MK-801 caused a 30% to 55% inhibition of PMA-induced increase in GPIIIa expression.