FIGURE 5.

Mechanism of S100A9 effect on MK differentiation. A, BM cells were isolated from WT, TLR4 KO, or RAGE KO mice and cultured in the presence of TPO with or without S100A9. Number of MKs was determined on day 5 of culture. B, BM cells from WT or TLR4 KO mice were kept in serum-free media with or without S100A9 for 2 hours. Activation of STAT5 was evaluated by Western blotting. C, WT BM cells were cultured in the presence of supernatants collected from BM cells from WT mice (WT-WT) or BM cells from S100A9 KO mice (KO-WT) without addition of TPO with or without 10 μmol/L TQ. Activation of STAT5 was evaluated by Western blotting. Experiment was repeated three times with similar results; results of two of them are shown. D, BM cells from WT or STAT5 KO mice were cultured in the presence of TPO with or without S100A9 protein for 5 days. Absolute number and proportion of MK were determined. Individual values, mean, and SEM values are shown. Statistics: ANOVA with Tukey multiple comparisons test.