Functional impact of Egr3 expression in HSPCs. (A) The gene expression pattern of Egr3 in hematopoietic cells at different stages. Data are represented as the mean ± SD (n = 3). (B) Diagram of the vectors used to express Egr3 in LKS⁺ cells. Egr3 cDNA was cloned into murine stem cell virus for subsequent transduction into cells. (C) Schematic of the overexpression experiments in LKS⁺ cells using the indicated retroviruses shown in Figure 7B. (D) LKS⁺ cells were treated as indicated in Figure 7C. GFP⁺ cell proliferation is shown. (E) Quantification of cells remaining in G0, as indicated in Figure 7C. Data are represented as the mean ± SEM (n = 6-8; 2 independent experiments). (F) Apoptotic analysis of LKS⁺ cells 48 hours after transduction with control or Egr3 retrovirus. Data are represented as the mean ± SEM (n = 6-8; 2 independent experiments). (G) The percentage of GFP⁺ donor cells in the PB of recipient mice at the indicated time points. Data are represented as the mean ± SD (n = 7-9). (H) In vitro liquid culture of Egr3-knockdown cells. Data are represented as the mean ± SEM (n = 8; 2 independent experiments). (I) The histogram shows changes in PB chimerism of GFP⁺ cells in recipients at the indicated time points after transplantation. In this assay, we did not sort the GFP⁺ cells after 48 hours of transduction. We directly injected the GFP⁺ and GFP⁻ cells into the recipients. The percentage of cells expressing GFP on the day of injection was normalized to 1. Data are represented as the mean ± SD (n = 6-8). (J) The cell cycle status of LKS⁺ cells in leukemic BM after Egr3 knockdown. Data are represented as the mean ± SEM (n = 8; 2 independent experiments). (K) Schematic of the response of HSCs to leukemia stress. The molecular mechanisms by which leukemia affects normal HSCs, as suggested by our studies, are indicated. IRES, internal ribosome entry site; LTR, long terminal repeats. *P < .05; **P < .01.