HSC/Ps with c-Myc deletion are biased toward megakaryocytic differentiation at the expense of other hematopoietic lineages. (A) CMPs, CLPs, and GMPs were significantly reduced in c-Myc^−/− mouse BM; however, the number of MEPs was less affected. (B) Increased percentages of CD71⁺ and CD41⁺ (arrow), 2 distinct populations of cells in BM of c-Myc^−/− mice. (C) Increased percentages of both CD41⁺c-kit⁻ and CD41⁺c-kit⁺ populations in c-Myc^−/− BM. (D) The absolute number of Mk-Ps (Lin⁻Sca1⁻CD41⁺c-kit⁺CD9⁺) is significantly increased in c-Myc^−/− BM (2 hind limbs), whereas the number of Ery-Ps (CD71⁺Ter119⁻) is less affected. However, the number of Ery-Bs (CD71⁺Ter119⁺) and differentiated nucleated Erys (CD71⁻Ter119⁺) is significantly reduced in c-Myc^−/− BM (2 hind limbs). (E) Proliferation of CD41⁺ megakaryocytes is less affected, whereas the proliferation of Gr1⁺ granulocytes is significantly decreased in c-Myc^−/− mice. (F) HSC/Ps from c-Myc^−/− mice express high levels of erythrocyte and megakaryocyte-specific genes, including Gata1, Fog1, and Eklf1, but reduced lymphoid and myeloid-specific genes, such as Pu.1. The expression levels of detected genes in c-Myc^−/− LSK and LK populations are shown relative to expression levels in the WT LSK cell population. The significant reduction of c-Myc levels in c-Myc^−/− HSC/Ps indicates the success of the induced c-Myc deletion. Data are an average of triplicate experiments. *P < .05; **P < .01.