Figure 4.

TPO/MPL signaling is required for the development of JAK2V617F MK-induced myeloproliferation. (A-B) Peripheral blood cell counts in WT control (Pf4⁺FF1⁻), Pf4⁺FF1⁺, TPO⁻ control (TPO⁻Pf4⁺FF1⁻), TPO⁻Pf4⁺FF1⁺, MPL⁻ control (MPL⁻Pf4⁺FF1⁻), and MPL⁻Pf4⁺FF1⁺ mice at 28 weeks of age (A) and 1 year of age (B). Data are presented as mean ±SEM; n = 6–11 mice per group. (C-D) At 28 weeks of age, marrow MKs (C) and marrow E-SLAM cells (D) were significantly increased in the Pf4⁺FF1⁺ mice compared to WT controls, but not in the TPO⁻Pf4⁺FF1⁺ mice or MPL⁻Pf4⁺FF1⁺ mice. Data are presented as mean ±SEM; n = 4–8 mice per group. (E-F) There was no correlation between Marrow MK and E-SLAM cell frequencies in TPO⁻Pf4⁺FF1⁺ (n = 4) (E) or MPL⁻Pf4⁺FF1⁺ (n = 5) mice (F). Data are presented as mean ±SEM. *P < 0.05.