Dose effect of PF4, TSP, and transforming growth factor β (TGF-β) on TPO mRNA expression.

PF4 (A), TSP (B), and TGF-β (C) were added to BM stromal cell cultures at increasing concentrations, resulting in inhibition of TPO mRNA expression. GAPDH level in cells exposed to PF4 is also shown (D). The results shown are the mean ± SD values from 4 separate experiments performed in triplicate. *P < .05 compared with controls.