Fig. 2. The effect of PD98059 and rapamycin on megakaryocytic morphology. (A) Cell morphology of MKs, derived from peripheral blood HPCs grown in serum-free liquid culture with 100 ng/mL TPO supplemented or not with 10 µM PD98059 or 50 nM rapamycin. Representative results from cells at day 12 of culture are shown (May-Grünwald staining; original magnification x400). (B) Effects of PD98059 or rapamycin treatment on polyploidization. The percentage of HPC-derived MKs with 1, 2, 4 or more than 8 lobes was evaluated by morphological analysis. The data relative to day 12 of culture are presented as the mean ± s.e.m. of six independent experiments. ^*P<0.05, ^**P<0.01, ^***P<0.001 when compared with the control by Student's t-test.