Comparison of c-mpl transcript levels in PLTs from control and TPO-stimulated mice by means of ribonuclease protection assays (2 μg). PLTs were isolated from mice grafted subcutaneously with FDC-P1 cells producing TPO (↑ PLT; A) or from mice in which the hematopoietic cells produce TPO (↑↑ PLT; B). Three (A) or two (B) independent platelet RNA preparations have been used.