Skp2 regulates stem cell pool size. (A) Analysis of the mRNA level of Skp2, N-Cadherin, and β-catenin in LT-HSCs from WT mice by real-time PCR (**P < .005; n = 4). (B) Analysis of the mRNA level of Skp2 LT-HSCs from WT and Skp2^−/− mice by real-time PCR (**P < .005; n = 4). (C) Total numbers of BM cells per mouse from WT and Skp2^−/− mice normalized by their body weights were 25.33 ± 6.22 million in WT BM cells versus 19.5 ± 5.49 million in Skp2^−/− BM cells (P > .05; n ≥ 4). (D) Analysis of LSK cell population from WT and Skp2^−/− mice by flow cytometry. The percentages of LSK cells in WT mice were 0.667% ± 0.058% versus 1.533% ± 0.322% in Skp2^−/− mice (*P < .05; n = 3). (E) Analysis of Flk⁻LSK population in WT and Skp2^−/− mice by flow cytometry. The percentages of Flk⁻LSK cells in WT mice were 39.5% ± 2.65% versus 52.8% ± 5.0% in Skp2^−/− mice (*P < .05; n = 3). (F) Analysis of GMP populations in WT and Skp2^−/− mice by flow cytometry. The percentages of GMP cells in WT mice were 1.45% ± 0.21% versus 3.43% ± 0.32% in Skp2^−/− mice (**P < .001; n = 4). (G) The CBC test was performed to determine the number of WBCs, RBCs, and platelets and the percentage of neutrophils and lymphocytes in WT and Skp2^−/− mice (P > .05; n = 5).