VEGF-A protein increased in BM fluids during G-CSF treatment, but VEGFR1 (Flt1), VEGFR2 (Kdr), and VEGFR3 (Flt4) mRNA are not detected in HSPCs. (A) VEGF-A concentration in BM fluids from mice mobilized with G-CSF. Data are mean ± standard deviation of 3 to 9 mice per time point. (B) RNA-seq analysis of LKS⁺ cells sorted from the BM of mice treated with saline or G-CSF for 2 days. Results in fragments per kilobase of transcript per million mapped reads (FKPM) are from 3 mice for each treatment group (mean ± standard deviation). (C) In silico single-cell clustering of expression of Flt1, Kdr, Flt4, and Vegfa mRNA on Single-Cell Gene Expression Atlas Web site (http://blood.stemcells.cam.ac.uk/single_cell_atlas.html). Distribution of individual HSPC subsets in blue (HSCs), yellow (LKS⁺ HSPCs), and red (LKS⁻ HPCs) (upper left panel). In all other panels, the intensity of the mRNA signal increases from gray (negative) to red. Slamf1 (CD150) and Procr (EPCR) mRNA identify long-term reconstituting HSCs. Among all single HSPCs sequenced (gray dots), the red dots represent single cells positive for the indicated mRNA. **P < .01.