Figure 3

Immunostaining of formalin-fixed, paraffin-embedded BM biopsies from prefibrotic PMF patients with the mouse monoclonal antibody CAL2. Nearly, all megakaryocytes in the case with genotypically demonstrated CALR mutation are strongly labelled (a; magnification: x200), whereas the megakaryocytes of the case without a CALR mutation remained unlabelled (b; magnification: x250). The CALR mutation status was confirmed by Sanger sequencing. In a, an unstained megakaryocyte is marked by an arrow.