β1 tubulin expression is associated with megakaryocytes forming proplatelets.

(A) Immunofluorescence analysis of primary wild-type fetal liver cell cultures performed with β1 tubulin-specific antiserum (left). Cells not forming proplatelets (arrows; including other blood cell lineages and immature megakaryocytes) are not stained. A phase-contrast image of the same microscopic field is shown on the right. (B) Semiquantitative RT-PCR analysis of β1 tubulin mRNA expressed in wild-type megakaryocytic colonies forming (+) or not forming (−) proplatelets, using primers specific for β1 tubulin and GAPDH (loading control). The numbers of PCR cycles are indicated. (C-F) Immunofluorescence analysis of individual cultured megakaryocytes (C), proplatelet fragments (D, E), and blood platelets (F) with β1 tubulin-specific antiserum. Scale bar, 5 μm.