Hmga2 expression promotes the repopulating ability and phenotypic reconstitution of JAK2^V617F-induced MPN. (A) Competitive repopulations (N = 3-7). Ly5.2⁺ H, J, or HJ BM cells with competitor Ly5.1⁺ WT BM cells at the ratio of 1:1 were injected into lethally irradiated Ly5.1⁺ mice. The ratios (percentage; vertical axis) of Ly5.2⁺ cells in lineages at the indicated time points (horizontal axis) after the first (left) and second (right) BMT are shown. BM cells collected 12 weeks after first BMT were injected for recipients of the secondary BMT. Among J (JAK2^V617F) mice (N = 7), BM cells from mice that achieved engraftment at the first BMT (red lines, N = 3) were exclusively referred to the second BMT. (B) Kaplan-Meier survival curves, (C) sternal BM histology, and (D) representative picture of the spleens of recipient mice at 12 weeks after the BMT, in BMT from the indicated transgenic mice without competitors (N = 6 for each). (B) P values were calculated by a log-rank test. (C) Hematoxylin-eosin (HE) and silver stains are shown (original magnification ×400). Scale bars indicate 50 µm. H, ΔHmga2; J, JAK2^V617F; HJ, ∆Hmga2/JAK2^V617F.