MF-initiating cells are present in the BM and spleen of JAK2^V617F/Ezh2^Δ/Δ mice. (a) Levels of TPO protein in the serum of WT (n = 6), Ezh2^Δ/Δ (n = 4), JAK2^V617F (n = 4), and JAK2^V617F/Ezh2^Δ/Δ (n = 4) mice 1–2 mo after the deletion of Ezh2. (b) qRT-PCR analysis of Il6 and Il1β in MEPs from WT (n = 6), Ezh2^Δ/Δ (n = 8), JAK2^V617F (n = 8), and JAK2^V617F/Ezh2^Δ/Δ (n = 8) mice 1–2 mo after the deletion of Ezh2. (c and d) Chimerism of CD45.2⁺ donor cells in Mac1⁺ myeloid cells, B220⁺ B cells, and CD4⁺/CD8⁺ T cells in the PB (c) and BM LSK cells (d) of CD45.1⁺ recipients (n = 5 each) at 3 mo after transplantation of BM and spleen LSKs isolated from WT and JAK2^V617F/Ezh2^Δ/Δ mice. (a–d) Bars and asterisks show the mean ± SEM and *, P < 0.05; **, P < 0.01; and ***, P < 0.001 by the Student’s t test; two independent experiments.