MYB and essential thrombocythemia: Interestingly, MYB down-regulation is responsible for enhanced normal and clonal megakaryopoiesis, as demonstrated by the fact that MYB knockdown in normal human hematopoietic progenitors promotes megakaryocyte development [50], and that MYB knockdown in the murine Kit+Sca1+Lin- hematopoietic stem cell population generates a transplantable myeloproliferative phenotype that mimics ET [51].