Tet2 haploinsufficiency decreases cell division in HSPCs. (A) Scheme of BrdU incorporation by HSCs. A 24-hour pulse of BrdU was administered to mice at 2 weeks after poly (I:C) treatment. Percentages of BrdU⁺ HSCs were analyzed by flow cytometry. (B) BrdU incorporation by HSCs from Nras^G12D/+, Tet2^+/−, Nras^G12D/+/Tet2^+/−, and littermate control mice (n = 4 per genotype). (C) GFP expression in HSCs, MPPs, and LSKs from Mx1-Cre/Tet2^+/−/Col1A1-H2B-GFP/Rosa26-M2-rtTA (Tet2^+/−) mice and littermate controls after labeling followed by 6 or 18 weeks of chase without doxycycline (doxy; n = 4 pairs of mice from 3 or 4 independent experiments). All mouse pairs were age and sex matched. Data represent mean ± standard error of the mean. Two-tailed Student t tests were used to assess statistical significance. *P ≤ .05, **P ≤ .01, ***P ≤ .001. MFI, mean fluorescence intensity.