MPL and myelofibrosis: Previous work has demonstrated that decreased expression of c‐Mpl on the cell surface of platelets or MKs is a critical feature of myelofibrosis or CAMT; thus, we sought to determine the level of c‐Mpl on the MK membrane in ITP.[15] First, we analyzed the bone marrow aspiration from ITP patients and found that the percentage of thromocytogenic megakaryocyte is decreased significantly, whereas the percentage of promegakaryocyte or granular megakaryocyte is increased, which suggested that the development of MK was delayed (Figure S1, Supporting Information).