Northern blot (A) and semi-quantitative RT-PCR analysis (B, C) of c-mpl and GPIIb mRNA expression in the platelets from ET patients (P1, P3, P4, P7, P9, P10, P12, and P14) and normal controls (C1, C2, and C4). (A) Four micrograms of total cellular RNA obtained from the platelets was electrophoresed in 1% agarose gels. The blot was hybridized with ³²P-labeled probe for c-mpl and then rehybridized with probes for GPIIb and β-actin. (B) Two-and-a-half micrograms of total cellular RNA was reverse-transcribed with oligo dT primers. Each of 1.5 μL of the cDNA product was amplified at various (20 to 34) cycles of PCR. (C) Expression levels of c-mpl and GPIIb mRNA was evaluated at 30 and 25 cycles of PCR, respectively.