(A)–(C) Related to Figure 5A–C. 8-Week-old WT-GFP, miRHET-GFP, and miRKO-GFP reporter mice were subjected to repeated intraperitoneal LPS stimulation (3 mg LPS/kg of body weight every other day) for 1 week. Percent of GFP+ cells in various lineages were quantified by FACS. Quantification of GFP+ cells in various lineages, including CD45+, CD19+, CD11b+, Gr1+, and CD3ε+, in bone marrow (A), spleen (B), and peripheral blood (C). (D)–(H) Age- and sex-matched WT, miR KO, p50 KO, and miR/p50 DKO mice were allowed to age to up to 18 months. Mice were harvested as they became moribund or at the end of the experiment. Spleen weight (D), Kaplan–Meier survival curve (E), and incidence of tumors (F). Representative histological images (H&E staining) of spleen (G) and femur bones (H) from 12-month-old female WT, miR KO, p50 KO, and miR/p50 DKO mice. Spleen from a miR-146a KO mouse with myeloid sarcoma was shown. Scale bars, 400 μm for spleens and 40 μm for bones. (I) Representative photographs of spleens from Rag2−/− Il2rg−/− mice transplanted with WT, miR KO, or miR/p50 DKO spleen cells. Scale bar, 1 cm. (J) 8-Week-old WT and miR KO mice were challenged with one dose of LPS (2 mg LPS/kg of body weight) intraperitoneally for 12 hr. 1 mg of BrdU was injected intraperitoneally. BrdU+ HSPCs were quantified by FACS. Representative FACS plots of BrdU+ LSK cells and LSK CD150+CD48− HSCs in bone marrow of WT and miR KO mice. No BrdU, no BrdU injection; basal state, no LPS injection; LPS stimulation, BrdU, and LPS injection.