Validation of candidate genes in murine hematopoietic stem and progenitor cells. (A) Gene-expression analysis of Pbx1, Fzd4, Hoxa10, Procr (Epcr), and Mycn in sorted LSK cells, CMPs, GMPs, and MEPs from wt C57BL/6J mice. Shown is the relative expression compared with expression of β-Actin (2^{-CT genes}/2^{-CT actin}; 3-5 independent cell sortings from BM of 2 pooled mice (C57Bl/6J) for each sort. PCR was performed on those samples (mean plus or minus standard deviation [SD]; 1-way ANOVA with Dunnett multiple comparisons test to the expression in LSK cell population [#P ≤ .05; ##P ≤ .01]). (B) Cell-surface expression of Epcr on LK, LSK, and LT-repopulating HSCs (LSK, CD48⁻, CD150⁺) from naive C57Bl/6J, Mpl^−/−, and Thpo^−/− mice. Endogenous Epcr was detected by antibody staining and flow cytometry (blue color, red color indicates the unstained control in the flow cytometry blots of wt BM) (n = 4-5; unpaired Student t test with Welsh correction [**P ≤ .01]). ActB, actin beta; CT, cycle threshold; n.d., not detectable.