Excess megakaryopoiesis in Cul5^fl/flVavCre mice is largely independent of Mpl and TPO. Numbers of (A) platelets (n = 21-28), (B) megakaryocytes per field from histological sections of sternal BM (n = 3-8) and (C) HSC (Lin^–Sca1⁺Kit⁺CD150⁺CD48^–, n = 3-17, left panel), CD41⁺HSC (n = 4-8, center panel) and percentage CD41⁺HSC in the HSC population (n = 4-8, right panel) in Cul5^fl/flVavCre, Cul5^fl/fl, Mpl^–/–Cul5^fl/flVavCre, Mpl^–/–Cul5^fl/fl, Thpo^–/–Cul5^fl/flVavCre, and Thpo^–/–Cul5^{+/+ or fl/fl} mice. Fold-differences in numbers of platelets, megakaryocytes, HSCs, and CD41⁺HSC between Cul5^fl/flVavCre and Cul5^fl/fl mice, Mpl^–/–Cul5^fl/flVavCre and Mpl Cul5^fl/fl mice or Thpo^–/–Cul5^fl/flVavCre and Thpo^–/–Cul5^{+/+ or fl/fl} mice are indicated above the bar graphs. (D) Numbers of MPP (Lin^–Sca1⁺Kit⁺CD150^–CD48^lo/–), HPC1 (Lin^–Sca1⁺Kit⁺CD150^–CD48⁺), HPC2 (Lin^–Sca1⁺Kit⁺CD150⁺CD48⁺), HPC1Flt3^hi and HPC1Flt3^lo cells (upper panel, n = 3-17), and CMP (Lin^–Sca1^–Kit⁺CD34⁺FcgRII/III^lo), GMP (Lin^–Sca1^–Kit⁺CD34⁺FcgRII/III⁺), MEP (Lin^–Sca1^–Kit⁺CD34^–FcgRII/III^–) and CFU-E (Lin^–Sca1^–Kit⁺CD150^–Endoglin^hiFcγRII/III^lo) (lower panel, n = 3-17) in Cul5^fl/flVavCre, Cul5^fl/fl, Mpl^–/–Cul5^fl/flVavCre, Mpl^–/–Cul5^fl/fl, Thpo^–/–Cul5^fl/flVavCre, and Thpo^–/–Cul5^{+/+ or fl/fl} mice. Each point represents data from an individual mouse, bars represent mean ± SD. ∗P < .05, ∗∗P < .01, ∗∗∗P < .001, ∗∗∗∗P < .0001 for comparison of Cul5^fl/flVavCre, Mpl^–/–Cul5^fl/flVavCre and Thpo^–/–Cul5^fl/flVavCre data with their respective Cul5^{+/+ or fl/fl} controls and Cul5^fl/flVavCre with Mpl^–/–Cul5^fl/flVavCre and Thpo^–/–Cul5^fl/flVavCre (1-way ANOVA with Dunnett’s correction for multiple comparisons). Data from Cul5^fl/flVavCre and Cul5^fl/fl are reproduced from Figure 1A-B,D and Figure 3C for comparison.