Psip1 excision perturbs the HSC compartments. (A) The proportion of BM corresponding to the HSC-containing LSK progenitors measured in Psip^Fl/Fl and Psip^Vav/Vav mice (4-7 animals per group, 8-10 weeks of age). Subsectioning according to CD34 and CD135 expression yielded phenotypic assessments of LT-HSC, ST-HSC, and MPP fractions. LT-HSC, long-term hematopoietic stem cells; MPP, multipotent progenitors; ST-HSC, short-term hematopoietic stem cells. (B) BM frequencies of the more differentiated progenitors gated in the LSK population, subsectioned based on CD16/32 and CD34 expression to compare common myeloid progenitors (CMPs), granulocyte-macrophage progenitors (GMPs), and megakaryocyte-erythroid progenitors (MEPs). The CLP fraction is gated based on CD127 expression. CLP, common lymphoid progenitors. (C) Percentage of BM cells at different steps in B-cell development. The frequencies of pre-pro-B, pro-B, pre-B, immature, and mature B cells in Psip^Fl/Fl and Psip^Vav/Vav mice are shown (4-7 animals per group). Mean values and SEM are shown. P values (*) show significance (*P < .05, **P < .01, ***P < .001, Student t test).