TPO and acute myeloid leukemia: However, there are infrequent but serious cases of progression to acute myeloid leukemia (AML) and BM fibrosis, possibly related to the expansion of abnormal hematopoietic stem cells [1, 5]; TPO has pivotal roles in megakaryopoiesis as well as the expansion of hematopoietic stem and progenitor cells (HSPCs).