Expression of p21waf1/cip1 and PF4 mRNA during short-term liquid culture of normal human megakaryocytes. Short-term liquid culture of normal human megakaryocytes was performed as described.17 18 The cells were harvested at the indicated time points and subjected to morphologic examination on Wright-Giemsa–staining cytospin slides (upper panel) and semiquantitative RT-PCR analysis for p21, PF4, and GAPDH mRNA expression (lower panel). The numbers of PCR cycles were set in each gene to show that the amount of amplified PCR product was directly proportional to the amount of input RNA (35 cycles for each gene). Amplified products were analyzed on 2% agarose gels followed by ethidium bromide staining. M, molecular size marker (BioMarker Low; Bio Ventures, Inc, Murfreesboro, TN).
