Effect of TPO on the expression of PAI-1 mRNA in UT-7/EPO transfected with c-Mpl (UT-7/EPO-MPL). (A) Total cellular RNAs extracted from UT-7/EPO, UT-7/EPO transfected with c-Mpl (UT-7/EPO-MPL), and UT-7/TPO were RT and amplified by PCR. The RT-PCR products were resolved by agarose gel electrophoresis, and the bands were transferred to a membrane and hybridized to³²P-labeled c-mpl P cDNA probes. (B) UT-7/EPO-MPL cells were cultured in the presence of 1 U/mL EPO or 10 ng/mL TPO. The cells were harvested at the indicated time points (0 to 28 days) and subjected to RT-PCR analysis for PAI-1 and GAPDH mRNA expression. PAI-1 RT-PCR products were analyzed on 2% agarose gels and transferred to membranes and hybridized to ³²P-labeled PAI-1 cDNA probes.