Decreased erythropoiesis potential in RHAU^fl/fl:vav-iCremice is because of decreased proliferation ability of ProEs. (A) Histogram showing the BrdU signals in ProEs. Most of the ProEs were BrdU⁺ in RHAU^fl/fl mice. In contrast, most of the ProEs are BrdU⁻ in mice lacking RHAU. (B) Percentage of BrdU⁺ cells from RHAU^fl/fl and RHAU^fl/fl:vav-iCre mice; *P < .05; n = 3. (C) Histogram showing CFSE signals. RHAU-ablated ProEs retained higher CFSE signals than wild-type ProEs after 3 days of culture. Freshly isolated ProEs were stained with CFSE on day 0 and cultured for 3 days in medium supplied with Epo to sustain proliferation. The wild-type ProEs showed the highest peak at a lower CFSE signal intensity, whereas the RHAU-ablated ProEs showed the highest peak at the highest CFSE signal. (D) Histogram showing annexin V binding activity of Ter-119⁺ erythroblasts isolated from the spleen.