Fbw7 deletion leads to a depletion of BM hematopoietic progenitors. (A) Absolute numbers of BM cells in polyI-polyC–injected control (Fbw7^f/f, MxCre⁻) and CKO (Fbw7^f/f, MxCre⁺) mice 2 wk after polyI-polyC deletion are shown. (B) Lin⁻ BM cells were stained for c-kit and Sca-1 to mark the LSK population (dot plot), and absolute LSK numbers (histogram) were calculated (also at 2 wk after polyI-polyC). (C) Quantitation of peripheral (spleen) LSKs 2 wk after polyI-polyC injection. P < 0.05. (D and E) Absence of enhanced rates of apoptosis as defined by a combination of 7-AAD/annexin V staining in either total BM of LSK cells (3 wk after polyI-polyC injection). (F) LSK cells were analyzed by FACS for CD34 expression to separate long-term (LT, CD34⁻) from short-term (ST, CD34⁺) HSCs. (G) MPs (Lin⁻/Sca-1⁻/c-kit⁺) were analyzed by FACS for CD34 and FcγRII/III expression to show common MPs (CMP, CD34⁺/ FcγRII/III⁻; bottom right gate), granulocyte/macrophage progenitors (GMP, CD34⁺/ FcγRII/III⁺; top right gate), and megakaryocyte/erythroid progenitors (MEP, CD34^lo / FcγRII/III⁻; bottom left gate). (H) Absolute number of mature (IgM⁺/B220^hi) and immature (IgM⁺/B220⁺) BM B cells are shown (2 wk after polyI-polyC). Error bars show the SD. Numbers indicate the percentage of cells in each gate. *, P < 0.05; **, P < 0.005. For all experiments, n = 8.