Loss of RHAU leads to progressive reduction in the population expansion ability of hematopoietic cells. (A) The numbers of ProE, Ery.A, Ery.B, and Ery.C cells in the BM and spleen are shown. The number at the top of each bar graph indicates the fold increase/decrease after RHAU ablation. *P < .05; n = 4. The order of cell differentiation in the erythrocytic lineage is indicated: ProE → Ery.A → Ery.B →Ery.C. (B) Effect of RHAU ablation on the number of stem cells. The mean numbers ± SEs of different cell types are shown as bar charts. The number at the top of each bar graph indicates the fold change after RHAU ablation. Arrows indicate the path of early hematopoiesis: LT-HSC → ST-HSC → LMPP or → CMP. *P < .05; n = 6. (C) The progressive reduction of RHAU-ablated hematopoietic cells in population expansion ability was shown in competitive repopulation assays. Two different combinations of BM cells, (i) UBC-GFP and RHAU^fl/fl in a 1:10 ratio or (ii) UBC-GFP and RHAU^fl/fl:MxCre in a 1:10 ratio, were transplanted into BL6.CD45.1 mice. The recipient mice were divided into 3 groups. Group 1 recipient mice were transplanted with UBC-GFP and RHAU^fl/fl cells (n = 3), group 2 recipient mice were transplanted with UBC-GFP and RHAU^fl/fl:MxCre cells (n = 4), and group 3 recipient mice were transplanted with UBC-GFP and RHAU^fl/fl:MxCre cells (n = 4). Mice from groups 1 and 2 were treated with polyI:C 5 weeks after BM transplantation and mice in group 3 were kept untreated; *P < .05.