MPIG6B and myelofibrosis: To examine G6B expression in bone marrow megakaryocytes in situ, immunohistochemical staining was performed on trephine biopsy sections from healthy donors and patients with mutCALR and JAK2V617F+ myelofibrosis, confirming the expected expression on control megakaryocytes but with a dramatic increase in G6B+ cells in myelofibrosis (Figure 7C).