The PV-like phenotype in JAK2^R/R mice is cell-intrinsic and the severity is dependent on homozygous JAK2V617F allele burden. (A) Plasma EPO level was significantly reduced in JAK2^R/R mice compared with JAK2^R/+ and WT littermates. (B) The PV-like phenotype in JAK2^R/R mice is transplantable. BM cells (2 × 10⁶ per recipient) were transplanted into irradiated 129SvEvBrd/C57Bl/6 F1 recipients. Donors were StellaCre^−/− background. Time course of blood counts are shown for 1 to 4 months following transplantation. Significant differences are indicated and were determined using a linear mixed-effect model. (C) The severity of the PV-like phenotype corresponds to JAK2^R/R donor cell chimerism (ie, homozygous-JAK2V617F allele burden). The graph shows a positive correlation between hematocrit and JAK2^R/R donor chimerism at 2 months posttransplantation. The data were analyzed by Spearman rank correlation coefficient test; r² and P values are indicated. (D) Kaplan-Meier analysis shows that JAK2^R/R mice have significantly reduced survival compared with both WT and JAK2^R/+ mice. (E) Kaplan-Meier analysis show that male JAK2^R/R mice have significantly reduced survival compared with female JAK2^R/R mice; P values are indicated. BMT, BM transplantation; WBC, white blood cell.