Ybx1 is dispensable for normal hematopoiesis. (A-C) Blood count analysis in the PB of WT and Ybx1^cKO mice at 4 weeks after pIpC treatment (n = 6) for white blood cells (WBC), lymphoma cells (LYM), granulocytes (GRA), monocytes (MON) (A), red blood cells (RBC) (B), and platelets (PLT) (C). (D) Percentages of different mature lineage cells in the PB of WT and Ybx1^cKO mice at 4 weeks after pIpC treatment (n = 6). (E) Representative fluorescence-activated cell sorting plots showing the gating strategy for different stem and progenitor cell populations in BM from WT and Ybx1^cKO mice. (F-G)) Frequencies (F) and total cell numbers (G) of different progenitor populations (left) and stem cell populations (right) in the bone marrow of WT and Ybx1^cKO mice 4 weeks after pIpC treatment (n = 4). (H-I) Colony formation assay showing similar clonogenic ability (H) and representative clone image (I) of Lin^– BM cells from WT and Ybx1^cKO mice at 4 weeks after pIpC treatment. (J-K) Competitive repopulation assay showing similar reconstitution capacity of HSCs from WT and Ybx1^cKO mice. (J) Total BM cells from WT and Ybx1^cKO mice were transplanted into lethally irradiated recipient mice (CD45.1) together with equal numbers of CD45.1 competitor BM cells. Flow cytometry analysis of different donor-derived cell lineages in PB of recipient mice from 4 to 16 weeks after BMT (WT, n = 5; Ybx1^cKO, n = 5). (K) Percentage of donor-derived stem cell (left) and progenitor cell (right) compartments in the BM of recipients at 16 weeks after BMT. Horizontal bars represent abbreviations for cell types (A-D,F-G,K-L), or show the weeks after bone marrow transplantation (J). Error bars denote mean ± SD. Two-tailed Student t test: *P < .05; ***P < .001. LT-HSC, long-term HSC; MkP, megakaryocyte progenitor; NS, not significant; Prog, Lin⁻c-Kit⁺ progenitor cells; Sca-1, stem cell antigen-1; ST-HSC, short-term HSC.