Tet2 loss accelerates the MPN phenotype of Jak2V617F mice. (A) Spleen weights of age-matched WT, Tet2^null, Jak2^VF, and Jak2^VF/Tet2^null mice 24 to 30 weeks old (mean ± standard error of the mean [SEM]; n = 4 in each group). (B) Photograph of spleens from Jak2^VF and Jak2^VF/Tet2^null mice. (C) Histopathologic sections of spleen from representative WT, Tet2^null, Jak2^VF, and Jak2^VF/Tet2^null mice (original magnification ×4; H&E stain). (D) Frequency of CD71⁺ Ter119⁺ erythroid precursor cells in spleen from age-matched WT, Tet2^null, Jak2^VF, and Jak2^VF/Tet2^null mice (mean ± SEM; n = 4 in each group). (E) Frequency of Mac1⁺ Gr1⁺ myeloid precursor cells in spleen from age-matched WT, Tet2^null, Jak2^VF, and Jak2^VF/Tet2^null mice (mean ± SEM; n = 4 in each group). (F) Frequency of CD150⁺ CD48⁻ LSK cells (LT-HSC), CD150⁻ CD48⁻ LSK cells (ST-HSC), and CD48⁺ LSK cells (MPP) in spleen from age-matched WT, Tet2^null, Jak2^VF, and Jak2^VF/Tet2^null mice (mean ± SEM; n = 4 in each group). *P < .05; **P < .005; ***P < .001.